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In the previous article, we described the mechanisms used by Trojan-Banker.AndroidOS.Gugi.c to bypass a number of new Android 6 security features. In this article, we review the entire Gugi mobile-banking Trojan family in more detail.The use of WebSocket by Gugi
The mobile-banking Trojan family, Trojan-Banker.AndroidOS.Gugi is interesting due to its use of the WebSocket protocol to interact with its command-and-control servers. This protocol combines the advantages of HTTP with those of commonly used sockets: there is no need to open extra ports on a device, as all the communication goes through standard port 80. At the same time, real-time data exchange is possible.
It is worth noting that even though this technology is user-friendly, it is not that popular among attackers. Among all the mobile Trojans that utilize WebSocket technology, more than 90% are related to the Gugi family.WebSocket Usage in Mobile SMS Trojans
We registered the first case of WebSocket technology use in mobile Trojans at the end of December 2013. It was Trojan-SMS.AndroidOS.FakeInst.fn. Judging by the code, the Trojan was created by the same malefactors who created the Trojan-Banker.AndroidOS.Gugi family.
During the initial registration, the FakeInst.fn Trojan uploads a large amount of device-related data to its server. The data includes the telephone number, the carrier information, IMEI, IMSI, etc.
From the server, the malware may receive a JSON file with the following commands (and data for the commands):
- SMS – send a text message with specified text to a specified number;
- intercept – enable or disable the interception of incoming SMS messages;
- adres – change a command-and-control server address;
- port – change a command-and-control server port;
- contacts – send a bulk SMS message with specified content to all the contact numbers listed on the infected device.
In addition, the Trojan steals all outgoing SMS messages.
In the middle of January 2014, just a couple of weeks after discovering FakeInst.fn, a new version of the Trojan appeared. The malware was no longer using WebSocket; instead the communication was performed with the help of the HTTP protocol (GET and POST requests). Among all the installation packages of the Trojan, we could discover only two (dating back to the middle of March 2014) that utilized WebSocket. Everything seemed to indicate that the attackers decided to drop the technology for a while. They started to use it again almost two years later, in the Gugi family.From SMS Trojans to Mobile Banking Trojans
Two years after finding the first version of Trojan-SMS.AndroidOS.FakeInst.fn, which utilized WebSocket, a new Websocket-using Trojan appeared, Trojan-Banker.AndroidOS.Gugi.a.
There are multiple matches in the Gugi code (variable and method names) with the Trojan-SMS.AndroidOS.FakeInst.fn code. The major changes within Gugi were the addition of a phishing window to steal the device user’s credit-card data and the use of WebSocket. Within all the Gugi mobile-banking Trojan family installation packages detected by us, WebSocket technology is used to communicate with the command-and-control server. Thus, the attackers had switched from Trojan-SMS to Trojan-Banker.Evolution of the Trojan-Banker.AndroidOS.Gugi
The evolution of the Gugi Trojan can be split into two stages:“Fanta”
The first stage started in the middle of December 2015. The word “Fanta” is used within the name of all versions of the Trojan related to this stage, for example, “Fanta v.1.0”.
On request from the command-and-control server, Gugi Trojan version 1.0 could perform the following actions:
- stop its operation;
- steal all the contacts from the device;
- steal all the SMS messages from the device;
- send an SMS message with specified text to a specified number;
- send a USSD request;
- steal SMS messages from a specified group/conversation.
In late December 2015, we spotted the next version of Gugi, “Fanta v.1.1”. Its major difference from the previous version was that the code had a way of disabling the phishing window (we would like to remind you that Gugi can also be used as an SMS Trojan). Another new feature allowed contacts to be added to the infected device at the request of the server. This version was spread much more actively than the first one.
At the beginning of February 2016, we detected two new versions of Gugi, “Fanta v2.0” and “Fanta v2.1”. These versions had an increased focus on banking. First, they came with a new phishing window for stealing the username and password from the mobile banking software of one of the largest Russian banks. Secondly, the Trojan code introduced the list of phone numbers of two Russian banks. All incoming SMS messages from these numbers were not only sent to the malefactors’ server (like other SMS messages) but were hidden from the user.
These versions had a phishing window, shown either on request from the server or right after the smartphone had booted up. The window would not close until the user had entered their data.
Then, in the middle of March 2016, we found “Fanta v.2.2”. This became the most popular version of al, accounting for more than 50% of all of the installation packages related to the “Fanta” stage. Starting from this version, phishing windows were drawn over banking applications and Google Play.
Phishing window over Google Play Store
One more phishing window started to appear, right before the window for stealing credit-card data. This window read: “Link your credit card to Google Play Store and get 200 rubles for any apps!”
Additionally, starting from this version, the Trojan actively fights its removal. If the malware has Device Administrator rights, then its removal is possible only after disabling those rights. Therefore, whenever the Trojan does not have Device Administrator rights, it aggressively demands such permission, drawing its window over the device settings window.
In April 2016, we found the most recent “Fanta” version to date, “Fanta v.2.3”. That version had only one significant change: if the user disables the Device Administrator rights for the Trojan, then the malware changes the device password, effectively blocking the device.
All versions of “Fanta” are detected by the Kaspersky Lab products as Trojan-Banker.AndroidOS.Gugi.a.“Lime”
The first file related to the second stage, “Lime”, was found a week before “Fanta v2.3” appeared, at the beginning of April 2016.
The installation package code for “Lime” seems to have been rewritten from the Fanta stage. The code, as well as the version names, had the word “Fanta” excluded and replaced with “Lime” in some lines. The same Trojan name, “Lime”, is seen in the administration panel through which the malefactors control this malware.
Trojan’s administration panel
Versions of the Trojan relating to the “Lime” stage do not change the device password when Device Administrator rights are disabled.
The first file discovered by us in April 2016 was version 1.1 and, judging by the code, was a test file. The next installation package related to the “Lime” stage was discovered in the middle of May 2016. It had the same version number, 1.1, but improved functionality.
The major change in version 1.1 of the “Lime” stage was that it showed new phishing windows. At that time, the Trojan could attack five banking apps of various Russian banks. Additionally, it had a new command to get the list of rules for processing incoming SMS messages. These rules define which messages should be hidden from the user and which messages should be replied to with specific messages.
Further, during the course of May 2016, we discovered files labelled 1.2 and 1.5 by the authors, even though the features of the files had not been changed.
Meanwhile, a new version of the Android OS, version 6.0, was released with security features that did not let the Trojan function properly. In June, we found a new version of the Trojan, 2.0, in which the malefactors had added support for Android 6. On Android 6 devices, the Trojan first requests permission to draw over other apps. Then, using the permission to its own advantage, it practically blocks the device, forcing the user to give Device Administrator rights to the malicious application as well as permission to read and send SMS messages and make calls.
Versions 3.0 and 3.1, which were found in July, have the same features as version 2.0 and utilize the same command-and-control server but different ports. Only one installation package for each version has been found by us. At the same time, version 2.0 continues to be actively spread.
All of the “Lime”-stage versions are detected by Kaspersky Lab products as Trojan-Banker.AndroidOS.Gugi.b and Trojan-Banker.AndroidOS.Gugi.c.Transmission
The Trojan is actively transmitted via SMS spam, with a link to phishing web pages that show a message indicating that the user has, supposedly, received an MMS picture.
Information about MMS message on phishing website
If the “show” button in the message is clicked, then the Trojan-Banker.AndroidOS.Gugi will be downloaded onto the device. It is highly likely that the name of the Trojan downloaded from such a websi фte will be similar to img09127639.jpg.apk.
As we have written in a previous post, we have encountered an explosive growth of Trojan-Banker.AndroidOS.Gugi attacks. August revealed 3 times as many users attacked by Gugi as in July, and almost 20 times as many as in June.
An amount of Kaspersky Lab mobile product users attacked by Trojan-Banker.AndroidOS.Gugi mobile-banking Trojan family
Today, the biggest number of attacks is performed by Lime version 2.0. All of the known active command-and-control servers of this Trojan are related to Lime versions 1.5 – 3.1. Not a single “Fanta” server known to us has been accessible since the middle of August 2016.
More than 93% of attacked users were located in Russia.MD5 of Malicious Files Mentioned in Article
We have already seen some cryptor attacks where malicious programs with different functions have been used in combination. For example, one version of the Shade cryptor checks victim computers for signs of accounting activity; if it finds any, it doesn’t encrypt the files, but instead installs remote control tools in the infected system. The bot can then be used by cybercriminals to steal money, a much more profitable outcome than just receiving a ransom to decrypt some files.
The owners of the RAA cryptor, however, took a different tack. The Trojan is delivered in emails that mostly target corporate users. After a successful infection, RAA executes its main task, i.e. encrypts the user’s files. However, it doesn’t stop there: some versions of RAA also include a Pony Trojan file, which steals confidential information from the infected computer. Using the stolen data, the cybercriminals can gain access to the victim’s mail clients and other resources. We can assume that the owners of RAA use these resources to carry out targeted attacks – sending out emails with the cryptor malware to the addresses on the victim’s contact list. This substantially improves the probability of subsequent infections.
In this article, we will provide details of how a pair of malicious programs – a new version of the RAA cryptor and the Pony stealer Trojan – work in unison.The RAA cryptor
We recently detected a new version of this Trojan that has a few differences from earlier known modifications. Let’s have a closer look at this particular sample, which has been assigned the verdict Trojan-Ransom.JS.RaaCrypt.ag.Propagation
The body of this new version of RAA is a script in JScript (with a .js file extension). The malicious script is sent to potential victims attached to a spam message in a ZIP file with the password ‘111’.
The attack is aimed primarily at corporate users: the message mimics finance-related business correspondence, and the script’s name is similar to those shown below:
Счета на оплату _ август 2016 согласовано и отправлено контрагенту для проведения оплаты _aytOkOTH.doc.js (Invoice_August 2016 approved and sent to contractor for payment _aytOkOTH.doc.js)
Счета на оплату _ август 2016 согласовано и отправлено контрагенту для проведения оплаты _EKWT.doc.js (Invoice_August 2016 approved and sent to contractor for payment _ EKWT.doc.js)
“Let’s presume we made a concession when we allowed you to postpone your due payment.
“We understand you may have difficulties, but do we have to wait for another two months? To be honest, we don’t really want to go to court. Please make all the payments in next few days.”
The message includes a notice saying:
“The company… notifies you that in line with internal security regulations, all outgoing emails are subject to asymmetric encryption. Dear client, your password for this message is 111.”
People who know what ‘asymmetric encryption’ is will probably just smile at this; however, the message is obviously targeting a different audience.
It should be noted that sending malicious content in a password-protected archive is a well-known trick used by cybercriminals to prevent anti-malware systems installed on mail servers from unpacking the archive and detecting any malicious content. To unpack an archive like this, the anti-malware product must automatically retrieve the password from the message, which isn’t always possible.
For an infection to occur, users have to unpack the archive themselves and launch the .js file.Script obfuscation
The code of the malicious script was deliberately obfuscated to complicate things for malware analysts. The content of the script looks like this in the source code:
Fragment of the obfuscated code
If we restore the line breaks and indents, it becomes obvious that the obfuscation involves renamed variables and functions, as well as strings hidden in the global array. After de-obfuscation and function renaming, the same section of code becomes much easier to read.
Fragment of de-obfuscated code
The script is nearly 3,000 lines long. Most of this is taken up by an implementation of the legitimate DLL CryptoJS, and an implementation of the RSA encryption procedure, which was also taken from public sources by the cybercriminals.How the Trojan works
To lull the victim into a false sense of security, the RAA cryptor demonstrates a fake Microsoft Word document immediately after it launches. This document is in fact an RTF file specially crafted by the cybercriminals. (The document is contained in the Trojan’s body encoded in Base64 format.)
The fake document displayed to the victim
While the user is reading the message about a document that’s supposedly not being displayed properly, the Trojan is doing its dirty work:
- Registers itself to be autostarted with Windows;
- Deletes the registry key associated with the VSS service (to prevent the restoring of files from shadow copies);
- Sends a request to the C&C server (unlike all previous versions of this Trojan, this version doesn’t wait for the delivery of keys from the server – the request is only sent so the cybercriminals can collect statistics);
- Proceeds to search for files and encrypts them.
Unlike earlier RAA modifications, this version of the cryptor does not request an encryption key from the C&C. Instead, the Trojan generates a session key on the client. To do so, it calls the WinAPI function RtlGenRandom which is considered a cryptographically secure generator of pseudorandom numbers.
To ensure it can call WinAPI functions from JS code, the Trojan uses a legitimate third-party OCX component called DynamicWrapperX. The Trojan stores it in its body in a Base64-encoded format, and installs it in the infected system. RAA has both 32-bit and 64-bit versions of DynamicWrapperX so it can attack systems running under both Windows architectures.
The Trojan encrypts the generated session key with an RSA algorithm (the public RSA-2048 key is contained within the script) and saves it to a file with the name “KEY-…”, where the multiple periods stand for a unique 36-character infection ID.File encryption
RAA searches for and encrypts files with the extensions .doc, .xls, .rtf, .pdf, .dbf, .jpg, .dwg, .cdr, .psd, .cd, .mdb, .png, .lcd, .zip, .rar, .csv whose names do not contain the substrings “.locked”, “~”, “$”.
When searching for files, the Trojan skips folders named “WINDOWS”, “RECYCLER”, “Program Files”, “Program Files (x86)”, “Windows”, “Recycle.Bin”, “RECYCLE.BIN”, “Recycler”, “TEMP”, “APPDATA”, “AppData”, “Temp”, “ProgramData”, and “Microsoft”.
When processing each file, RAA uses the session key to generate a file key and initialization vector (IV). The contents of the files are encrypted in different ways depending on the file size:
- 0 to 6,122 bytes: the file is encrypted in full.
- 6,123 to 4,999,999 bytes: three fragments are selected for encryption in different sections of the file. The first, 2000- to 2040-byte fragment is selected at the beginning of file; the location and size of the two other fragments depend on the size of the first fragment and the overall size of the file.
- 5,000,001 to 500,000,000 bytes: two fragments of 90000-125000 bytes are selected for encryption (from the beginning and end of the file).
- 500,000,001 bytes and larger: not encrypted.
A string is added at the end of the encrypted file that contains “IDNUM” (infection ID), “KEY_LOGIC” (indexes to construct the file key from the session key), “IV_LOGIC” (indexes to construct the IV from the session key), and “LOGIC_ID” (possible values are “1”, “2” or “3” – the selected encryption method depending on the file size). The encrypted file is given the additional extension .locked.
The string added to the end of the encrypted fileRansom demand
When the files are encrypted, RAA displays a file with the cybercriminals’ demands and contacts in WordPad. The Trojan fills the text template with a 36-character ID which is unique for each case.
The file containing the cybercriminals’ demands
The cybercriminals suggest that the victims purchase a file decryption key and software from them. Two methods of communication are available: email and the Bitmessage service. The victim is expected to pay for the decryption key in bitcoins.Plus a stealer Trojan
The damage caused by the Trojan is not limited to encrypting files. Like some of the earlier versions of RAA, the version we are examining has some added features. The Trojan contains an executable file encoded in Base64, which it writes to the hard drive at ‘C:\Users\<username>\Documents\ii.exe’ and launches after it has finished encrypting files. Analysis revealed that ‘ii.exe’ is none other than Pony, a known password-stealing Trojan (detection verdict: Trojan-PSW.Win32.Tepfer.gen).
Pony has proved to be an unusually long-lived Trojan. Its early versions supposedly emerged back in 2011, while in December 2013, as reported by the mass media, it stole the credentials of over 2 million users.
Naturally, after all that time Pony’s source code appeared on the web at some point. Analysis showed that the executable file we are analyzing here was constructed using Pony source code.Pony: confidential data theft
To recap, Pony’s main task is to collect confidential information from an infected computer and then send it to the cybercriminals.
Step 1. Stealing information
Below is a short list of the information that Pony hunts for.
- Passwords stored in web browsers
- Credentials to dozens of the most popular FTP clients
- Accounts with the most widespread mail clients
- Various cryptocurrency wallet files
The Trojan also has the following capabilities:
- Pony steals the user’s digital certificates.
- Pony stores a list of the most widespread combinations that users use as passwords. Using this list, it attempts to gain access to the accounts on an infected computer.
Step 2. Data encryption and sending
Before sending the collected information to cybercriminals, Pony encrypts it using the RC4 algorithm. When doing so, the Trojan keeps records of the checksums for the obtained data (slightly modified results of the CRC32 algorithm are used.) The sequence is as follows:
- Calculate the checksum of the non-encrypted data.
- Write the obtained value next to the input data.
- Encrypt input data with the RC4 algorithm using the key that the cybercriminals specified when they compiled the Trojan.
- Calculate the checksum of the encrypted data.
- Write the obtained value next to the input data.
- Generate a random 4-byte key
- Encrypt the input data with the RC4 algorithm using the generated key.
- Generate a data package ready for sending that can be described with a ToSend structure (see below)
A non-encrypted fragment of the generated report
Fragment of the report that is ready for sending. The encryption key is highlighted in red
When the data is brought up to the required form, Pony sends it to the cybercriminals.MD5
- Backdoor.OSX.Mokes.a is the most recently discovered OS X variant of a cross-platform backdoor which is able to operate on all major operating systems (Windows,Linux,OS X). Please see also our analysis on the Windows and Linux variants.
- This malware family is able to steal various types of data from the victim’s machine (Screenshots, Audio-/Video-Captures, Office-Documents, Keystrokes)
- The backdoor is also able to execute arbitrary commands on the victim’s computer
- To communicate it’s using strong AES-256-CBC encryption
Back in January this year we found a new family of cross-platform backdoors for desktop environments. After the discovery of the binaries for Linux and Windows systems, we have now finally come across the OS X version of Mokes.A. It is written in C++ using Qt, a cross-platform application framework, and is statically linked to OpenSSL. This leads to a filesize of approx. 14MB. Let’s have a look into this very fresh sample.
Its filename was “unpacked” when we got our hands on it, but we’re assuming that in-the-wild it comes packed, just like its Linux variant.
When executed for the first time, the malware copies itself to the first available of the following locations, in this order:
- $HOME/Library/App Store/storeuserd
Corresponding to that location, it creates a plist-file to achieve persistence on the system:
After that it’s time to establish a first connection with its C&C server using HTTP on TCP port 80:
The User-Agent string is hardcoded in the binary and the server replies to this “heartbeat” request with “text/html” content of 208 bytes in length. Then the binary establishes an encrypted connection on TCP port 443 using the AES-256-CBC algorithm.
Its next task is to setup the backdoor features:
- Capturing Audio
- Monitoring Removable Storage
- Capturing Screen (every 30 sec.)
- Scanning the file system for Office documents (xls, xlsx, doc, docx)
The attacker controlling the C&C server is also able to define own file filters to enhance the monitoring of the file system as well as executing arbitrary commands on the system.
Just like on other platforms, the malware creates several temporary files containing the collected data if the C&C server is not available.
- $TMPDIR/ss0-DDMMyy-HHmmss-nnn.sst (Screenshots)
- $TMPDIR/aa0-DDMMyy-HHmmss-nnn.aat (Audiocaptures)
- $TMPDIR/kk0-DDMMyy-HHmmss-nnn.kkt (Keylogs)
- $TMPDIR/dd0-DDMMyy-HHmmss-nnn.ddt (Arbitrary Data)
DDMMyy = date: 070916 = 2016-09-07
HHmmss = time: 154411 = 15:44:11
nnn = milliseconds
If the environment variable $TMPDIR is not defined, “/tmp/” is used as the location (http://doc.qt.io/qt-4.8/qdir.html#tempPath).Hints from the author
The author of this malware again left some references to the corresponding source files:
We detect this type of malware as HEUR:Backdoor.OSX.Mokes.aIOCs
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
Almost every Android OS update includes new security features designed to make cybercriminals’ life harder. And, of course, the cybercriminals always try to bypass them.
We have found a new modification of the mobile banking Trojan, Trojan-Banker.AndroidOS.Gugi.c that can bypass two new security features added in Android 6: permission-based app overlays and a dynamic permission requirement for dangerous in-app activities such as SMS or calls. The modification does not use any vulnerabilities, just social engineering.Initial infection
The Gugi Trojan is spread mainly by SMS spam that takes users to phishing webpages with the text “Dear user, you receive MMS-photo! You can look at it by clicking on the following link”.
Clicking on the link initiates the download of the Gugi Trojan onto the user’s Android device.Circumventing the security features
To help protect users from the impо, неact of phishing and ransomware attacks, Android 6 introduced a requirement for apps to request permission to superimpose their windows/views over other apps. In earlier versions of the OS they were able to automatically overlay other apps.
The Trojan’s ultimate goal is to overlay banking apps with phishing windows in order to steal user credentials for mobile banking. It also overlays the Google Play Store app to steal credit card details.
The Trojan-Banker.AndroidOS.Gugi.c modification gets the overlay permission it needs by forcing users to grant this permission. It then uses that to block the screen while demanding ever more dangerous access.
The first thing an infected user is presented with is a window with the text “Additional rights needed to work with graphics and windows” and one button: “provide.”
After clicking on this button, the user will see a dialog box that authorizes the app overlay (“drawing over other apps”).
System request to permit Trojan-Banker.AndroidOS.Gugi.c to overlay other apps
But as soon as the user gives Gugi this permission, the Trojan will block the device and show its window over any other windows/dialogs.
Trojan-Banker.AndroidOS.Gugi.c window that blocks the infected device until it receives all the necessary rights
It gives the user no option, presenting a window that contains only one button: “Activate”. Once the user presses this button they will receive a continuous series of requests for all the rights the Trojan is looking for. They won’t get back to the main menu until they have agreed to everything.
For example, following the first click of the button, the Trojan will ask for Device Administrator rights. It needs this for self-defense because it makes it much harder for the user to uninstall the app.
After successfully becoming the Device Administrator, the Trojan produces the next request. This one asks the user for permission to send and view SMS and to make calls.
It is interesting that Android 6 has introduced dynamic request capability as a new security features
Earlier versions of the OS only show app permissions at installation; but, starting from Android 6, the system will ask users for permission to execute dangerous actions like sending SMS or making calls the first time they are attempted, or allows apps to ask at any other time – so that is what the modified Gugi Trojan does.
TSystem request for dynamic permission
The Trojan will continue to ask the user for each permission until they agree. Should the user deny permission, subsequent requests will offer them the option of closing the request. If the Trojan does not receive all the permissions it wants, it will completely block the infected device. In such a case the user’s only option is to reboot the device in safe mode and try to uninstall the Trojan.
TRepeating system request for dynamic permissionA standard banking Trojan
With the exception of its ability to bypass Android 6 security features, and its use of the Websocket protocol, Gugi is a typical banking Trojan. It overlays apps with phishing windows to steal credentials for mobile banking or credit card details. It also steals SMS, contacts, makes USSD requests and can send SMS by command from the CnC.
The Trojan-Banker.AndroidOS.Gugi family has been known about since December 2015, with the modification Trojan-Banker.AndroidOS.Gugi.c first discovered in June 2016.Victim profile
The Gugi Trojan mainly attacks users in Russia: more than 93% of attacked users to date are based in that country. Right now it is a trending Trojan – in the first half of August 2016 there were ten times as many victims as in April 2016.
TUnique number users attacked by Trojan-Banker.AndroidOS.Gugi.
We will shortly be publishing a detailed report into the Trojan-Banker.AndroidOS.Gugi malware family, its functionality and its use of the Websocket protocol.
All Kaspersky Lab products detect all modifications of the Trojan-Banker.AndroidOS.Gugi malware family.
For malware writers, Google Play is the promised land of sorts. Once there, a malicious application gains access to a wide audience, gains the trust of that audience and experiences a degree of leniency from the security systems built into operating systems. On mobile devices, users typically cannot install applications coming from sources other than the official store, meaning this is a serious barrier for an app with malicious intent. However, it is far from easy for the app to get into Google Play: one of the main conditions for it is to pass a rigorous check for unwanted behavior by different analysis systems, both automatic and manual.
Some malware writers have given up on their efforts to push their malicious creations past security checks, and instead learned how to use the store’s client app for their unscrupulous gains. Lately, we have seen many Trojans use the Google Play app during promotion campaigns to download, install and launch apps on smartphones without the owners’ knowledge, as well as leave comments and rate apps. The apps installed by the Trojan do not typically cause direct damage to the user, but the victim may have to pay for the created excessive traffic. In addition, the Trojans may download and install paid apps as if they were free ones, further adding to the users’ bills.
Let us look into the methods how such manipulations with Google Play happen.Level 1. N00b
The first method is to make the official Google Play app store undertake the actions the cybercriminal wants. The idea is to use the Trojan to launch the client, open the page of the required app in it, then search for and use special code to interact with the interface elements (buttons) to cause download, installation and launch of the application. The misused interface elements are outlined with red boxes in the screenshots below:
The exact methods of interaction with the interface vary. In general, the following techniques may be identified:
- Use of the Accessibility services of the operating system (used by modules in Trojan.AndroidOS.Ztorg).
- Imitation of user input (used by Trojan-Clicker.AndroidOS.Gopl.c).
- Code injection into the process of Google Play client to modify its operation (used by Trojan.AndroidOS.Iop).
To see how such Trojans operate. Let us look at the example of Trojan.AndroidOS.Ztorg.n. This malicious program uses Accessibility services originally intended to create applications to help people with disabilities, such as GUI voice control apps. The Trojan receives a job from the command and control server (C&C) which contains a link to the required application, opens it in Google Play, and then launches the following code:
This code is needed to detect when the required interface element appears on the screen, and to emulate the click on it. This way, the following buttons are clicked in a sequence: “BUY” (the price is shown in the button), “ACCEPT” and “CONTINUE”. This is sufficient to purchase the app, if the user has a credit card with sufficient balance connected to his/her Google account.Level 2. Pro
Some malware writers take roads less traveled. Instead of using the easy and reliable way described above, they create their own client for the app store using HTTPS API.
The difficult part about this approach is that the operation of the self-made client requires information (e.g. user credentials and authentication tokens) which is not available to a regular app. However, the cybercriminals are very fortunate that all required data are stored on the device in clear text, in the convenient SQLite format. Access to the data is limited by the Android security model, however apps may abuse it e.g. by rooting the device and thus gaining unlimited access.
For example, some versions of the Trojan.AndroidOS.Guerrilla.a have their own client for Google Play, which is distributed with the help of the rooter Leech. This client successfully fulfils the task of downloading and installing free and paid apps, and is capable of rating apps and leaving comments in the Google store.
After launch, Guerrilla starts to collect the following required information:
The credentials to the user’s Google Play account.
Activities in Google Play require special tokens that are generated when the user logs in. When the user is already logged in to Google Play, the Trojan can use the locally cached tokens. They can be located through a simple search through the database located at /data/system/users/0/accounts.db:
With the help of the code below, the Trojan checks if there are ready tokens on the infected device, i.e. if the user has logged on and can do activities in Google Play:
If no such tokens are available, the Trojan obtains the user’s username and hashed password, and authenticates via OAuth:
- Android_id is the device’s unique ID.
Google Service Framework ID is the device’s identifier across Google services.
First, the Trojans attempts to obtain this ID using regular methods. If these fail for whatever reason, it executes the following code:
Google Advertising ID is the unique advertising ID provided by Google Play services.
Guerrilla obtains it as follows:
In a similar way, the Trojan obtains hashed data about the device from the file “/data/data/com.google.android.gms/shared_prefs/Checkin.xml“.
When the Trojan has collected the above data, it begins to receive tasks to download and install apps. Below is the structure of one such task:
The Trojan downloads the application by sending POST requests using the links below:
- https://android.clients.google.com/fdfe/search: a search is undertaken for the request sent by the cybercriminals. This request is needed to simulate the user’s interaction with the Google Play client. (The main scenario of installing apps from the official client presupposes that the user first does the search request and only then visits the app’s page).
- https://android.clients.google.com/fdfe/details: with this request, additional information needed to download the app is collected.
- https://android.clients.google.com/fdfe/purchase: the token and purchase details are downloaded, used in the next request.
- https://android.clients.google.com/fdfe/delivery: the Trojan receives the URL and the cookie-files required to download the Android application package (APK) file.
- https://android.clients.google.com/fdfe/log: the download is confirmed (so the download counter is incremented.)
- https://android.clients.google.com/fdfe/addReview: the app is rated and a comment is added.
When creating the requests, the cybercriminals attempted to simulate most accurately the equivalent requests sent by the official client. For example, the below set of HTTP headers is used in each request:
After the request is executed, the app may (optionally) get downloaded, installed (using the command ‘pm install -r’ which allows for installation of applications without the user’s consent) and launched.Conclusion
The Trojans that use the Google Play app to download, install and launch apps from the store to a smartphone without the device owner’s consent are typically distributed by rooters – malicious programs which have already gained the highest possible privileges on the device. It is this particular fact that allows them to launch such attacks on the Google Play client app.
This type of malicious program pose a serious threat: in Q2 2016, different rooters occupied more than a half of the Top 20 of mobile malware. All the more so, rooters can download not only malicious programs that compromise the Android ecosystem and spend the user’s money on purchasing unnecessary paid apps, but other malware as well.
In early June, 2016, the Russian police arrested the alleged members of the criminal group known as Lurk. The police suspected Lurk of stealing nearly three billion rubles, using malicious software to systematically withdraw large sums of money from the accounts of commercial organizations, including banks. For Kaspersky Lab, these arrests marked the culmination of a six-year investigation by the company’s Computer Incidents Investigation team. We are pleased that the police authorities were able to put the wealth of information we accumulated to good use: to detain suspects and, most importantly, to put an end to the theft. We ourselves gained more knowledge from this investigation than from any other. This article is an attempt to share this experience with other experts, particularly the IT security specialists in companies and financial institutions that increasingly find themselves the targets of cyber-attacks.
When we first encountered Lurk, in 2011, it was a nameless Trojan. It all started when we became aware of a number of incidents at several Russian banks that had resulted in the theft of large sums of money from customers. To steal the money, the unknown criminals used a hidden malicious program that was able to interact automatically with the financial institution’s remote banking service (RBS) software; replacing bank details in payment orders generated by an accountant at the attacked organization, or even generating such orders by itself.
In 2016, it is hard to imagine banking software that does not demand some form of additional authentication, but things were different back in 2011. In most cases, the attackers only had to infect the computer on which the RBS software was installed in order to start stealing the cash. Russia’s banking system, like those of many other countries, was unprepared for such attacks, and cybercriminals were quick to exploit the security gap.
We participated in the investigation of several incidents involving the nameless malware, and sent samples to our malware analysts. They created a signature to see if any other infections involving it had been registered, and discovered something very unusual: our internal malware naming system insisted that what we were looking at was a Trojan that could be used for many things (spamming, for example) but not stealing money.
Our detection systems suggest that a program with a certain set of functions can sometimes be mistaken for something completely different. In the case of this particular program the cause was slightly different: an investigation revealed that it had been detected by a “common” signature because it was doing nothing that could lead the system to include it in any specific group, for example, that of banking Trojans.
Whatever the reason, the fact remained that the malicious program was used for the theft of money.
So we decided to take a closer look at the malware. The first attempts to understand how the program worked gave our analysts nothing. Regardless of whether it was launched on a virtual or a real machine, it behaved in the same way: it didn’t do anything. This is how the program, and later the group behind it, got its name. To “lurk” means to hide, generally with the intention of ambush.
We were soon able to help investigate another incident involving Lurk. This time we got a chance to explore the image of the attacked computer. There, in addition to the familiar malicious program, we found a .dll file with which the main executable file could interact. This was our first piece of evidence that Lurk had a modular structure.
Later discoveries suggest that, in 2011, Lurk was still at an early stage of development. It was formed of just two components, a number that would grow considerably over the coming years.
The additional file we uncovered did little to clarify the nature of Lurk. It was clear that it was a Trojan targeting RBS and that it was used in a relatively small number of incidents. In 2011, attacks on such systems were starting to grow in popularity. Other, similar, programs were already known about, the earliest detected as far back as in 2006, with new malware appearing regularly since then. These included ZeuS, SpyEye, and Carberp, etc. In this series, Lurk represented yet another dangerous piece of malware.
It was extremely difficult to make Lurk work in a lab environment. New versions of the program appeared only rarely, so we had few opportunities to investigate new incidents involving Lurk. A combination of these factors influenced our decision to postpone our active investigation into this program and turn our attention to more urgent tasks.A change of leader
For about a year after we first met Lurk, we heard little about it. It later turned out that the incidents involving this malicious program were buried in the huge amount of similar incidents involving other malware. In May 2011, the source code of ZeuS had been published on the Web and this resulted in the emergence of many program modifications developed by small groups of cybercriminals.
In addition to ZeuS, there were a number of other unique financial malware programs. In Russia, there were several relatively large cybercriminal groups engaged in financial theft via attacks on RBS. Carberp was the most active among them. At the end of March 2012, the majority of its members were arrested by the police. This event significantly affected the Russian cybercriminal world as the gang had stolen hundreds of millions of rubles during a few years of activity, and was considered a “leader” among cybercriminals. However, by the time of the arrests, Carberp’s reputation as a major player was already waning. There was a new challenger for the crown.
A few weeks before the arrests, the sites of a number of major Russian media, such as the agency “RIA Novosti”, Gazeta.ru and others, had been subjected to a watering hole attack. The unknown cybercriminals behind this attack distributed their malware by exploiting a vulnerability in the websites’ banner exchange system. A visitor to the site would be redirected to a fraudulent page containing a Java exploit. Successful exploitation of the vulnerability initiated the launch of a malicious program whose main function was collecting information on the attacked computer, sending it to a malicious server, and in some cases receiving and installing an extra load from the server.
The code on the main page of RIA.ru that is used to download additional content from AdFox.ru
From a technical perspective, the malicious program was unusual. Unlike most other malware, it left no traces on the hard drive of the system attacked and worked only in the RAM of the machine. This approach is not often used in malware, primarily because the resulting infection is “short-lived”: malware exists in the system only until the computer is restarted, at which point the process of infection need to be started anew. But, in the case of these attacks, the secret “bodiless” malicious program did not have to gain a foothold in the victim’s system. Its primary job was to explore; its secondary role was to download and install additional malware. Another fascinating detail was the fact that the malware was only downloaded in a small number of cases, when the victim computer turned out to be “interesting”.
Part of the Lurk code responsible for downloading additional modules
Analysis of the bodiless malicious program showed that it was “interested” in computers with remote banking software installed. More specifically, RBS software created by Russian developers. Much later we learned that this unnamed, bodiless module was a mini, one of the malicious programs which used Lurk. But at the time we were not sure whether the Lurk we had known since 2011, and the Lurk discovered in 2012, were created by the same people. We had two hypotheses: either Lurk was a program written for sale, and both the 2011 and 2012 versions were the result of the activity of two different groups, which had each bought the program from the author; or the 2012 version was a modification of the previously known Trojan.
The second hypothesis turned out to be correct.Invisible war with banking software
A small digression. Remote banking systems consist of two main parts: the bank and the client. The client part is a small program that allows the user (usually an accountant) to remotely manage their organization’s accounts. There are only a few developers of such software in Russia, so any Russian organization that uses RBS relies on software developed by one of these companies. For cybercriminal groups specializing in attacks on RBS, this limited range of options plays straight into their hands.
In April 2013, a year after we found the “bodiless” Lurk module, the Russian cybercriminal underground exploited several families of malicious software that specialized in attacks on banking software. Almost all operated in a similar way: during the exploration stage they found out whether the attacked computer had the necessary banking software installed. If it did, the malware downloaded additional modules, including ones allowing for the automatic creation of unauthorized payment orders, changing details in legal payment orders, etc. This level of automation became possible because the cybercriminals had thoroughly studied how the banking software operated and “tailored” their malicious software modules to a specific banking solution.
The people behind the creation and distribution of Lurk had done exactly the same: studying the client component of the banking software and modifying their malware accordingly. In fact, they created an illegal add-on to the legal RBS product.
Through the information exchanges used by people in the security industry, we learned that several Russian banks were struggling with malicious programs created specifically to attack a particular type of legal banking software. Some of them were having to release weekly patches to customers. These updates would fix the immediate security problems, but the mysterious hackers “on the other side” would quickly release a new version of malware that bypassed the upgraded protection created by the authors of the banking programs.
It should be understood that this type of work – reverse-engineering a professional banking product – cannot easily be undertaken by an amateur hacker. In addition, the task is tedious and time-consuming and not the kind to be performed with great enthusiasm. It would need a team of specialists. But who in their right mind would openly take up illegal work, and who might have the money to finance such activities? In trying to answer these questions, we eventually came to the conclusion that every version of Lurk probably had an organized group of cybersecurity specialists behind it.
The relative lull of 2011-2012 was followed by a steady increase in notifications of Lurk-based incidents resulting in the theft of money. Due to the fact that affected organizations turned to us for help, we were able to collect ever more information about the malware. By the end of 2013, the information obtained from studying hard drive images of attacked computers as well as data available from public sources, enabled us to build a rough picture of a group of Internet users who appeared to be associated with Lurk.
This was not an easy task. The people behind Lurk were pretty good at anonymizing their activity on the network. For example, they were actively using encryption in everyday communication, as well as false data for domain registration, services for anonymous registration, etc. In other words, it was not as easy as simply looking someone up on “Vkontakte” or Facebook using the name from Whois, which can happen with other, less professional groups of cybercriminals, such as Koobface. The Lurk gang did not make such blunders. Yet mistakes, seemingly insignificant and rare, still occurred. And when they did, we caught them.
Not wishing to give away free lessons in how to run a conspiracy, I will not provide examples of these mistakes, but their analysis allowed us to build a pretty clear picture of the key characteristics of the gang. We realized that we were dealing with a group of about 15 people (although by the time it was shut down, the number of “regular” members had risen to 40). This team provided the so-called “full cycle” of malware development, delivery and monetization – rather like a small, software development company. At that time the “company” had two key “products”: the malicious program, Lurk, and a huge botnet of computers infected with it. The malicious program had its own team of developers, responsible for developing new functions, searching for ways to “interact” with RBS systems, providing stable performance and fulfilling other tasks. They were supported by a team of testers who checked the program performance in different environments. The botnet also had its own team (administrators, operators, money flow manager, and other partners working with the bots via the administration panel) who ensured the operation of the command and control (C&C) servers and protected them from detection and interception.
Developing and maintaining this class of malicious software requires professionals and the leaders of the group hunted for them on job search sites. Examples of such vacancies are covered in my article about Russian financial cybercrime. The description of the vacancy did not mention the illegality of the work on offer. At the interview, the “employer” would question candidates about their moral principles: applicants were told what kind of work they would be expected to do, and why. Those who agreed got in.
A fraudster has advertised a job vacancy for java / flash specialists on a popular Ukrainian website. The job requirements include a good level of programming skills in Java, Flash, knowledge of JVM / AVM specifications, and others. The organizer offers remote work and full employment with a salary of $2,500.
So, every morning, from Monday to Friday, people in different parts of Russia and Ukraine sat down in front of their computer and started to “work”. The programmers “tuned” the functions of malware modifications, after which the testers carried out the necessary tests on the quality of the new product. Then the team responsible for the botnet and for the operation of the malware modules and components uploaded the new version onto the command server, and the malicious software on botnet computers was automatically updated. They also studied information sent from infected computers to find out whether they had access to RBS, how much money was deposited in clients’ accounts, etc.
The money flow manager, responsible for transferring the stolen money into the accounts of money mules, would press the button on the botnet control panel and send hundreds of thousands of rubles to accounts that the “drop project” managers had prepared in advance. In many cases they didn’t even need to press the button: the malicious program substituted the details of the payment order generated by the accountant, and the money went directly to the accounts of the cybercriminals and on to the bank cards of the money mules, who cashed it via ATMs, handed it over to the money mule manager who, in turn, delivered it to the head of the organization. The head would then allocate the money according to the needs of the organization: paying a “salary” to the employees and a share to associates, funding the maintenance of the expensive network infrastructure, and of course, satisfying their own needs. This cycle was repeated several times.
Each member of the typical criminal group has their own responsibilities.
These were the golden years for Lurk. The shortcomings in RBS transaction protection meant that stealing money from a victim organization through an accountant’s infected machine did not require any special skills and could even be automated. But all “good things” must come to an end.The end of “auto money flow” and the beginning of hard times
The explosive growth of thefts committed by Lurk and other cybercriminal groups forced banks, their IT security teams and banking software developers to respond.
First of all, the developers of RBS software blocked public access to their products. Before the appearance of financial cybercriminal gangs, any user could download a demo version of the program from the manufacturer’s website. Attackers used this to study the features of banking software in order to create ever more tailored malicious programs for it. Finally, after many months of “invisible war” with cybercriminals, the majority of RBS software vendors succeeded in perfecting the security of their products.
At the same time, the banks started to implement dedicated technologies to counter the so-called “auto money flow”, the procedure which allowed the attackers to use malware to modify the payment order and steal money automatically.
By the end of 2013, we had thoroughly explored the activity of Lurk and collected considerable information about the malware. At our farm of bots, we could finally launch a consistently functioning malicious script, which allowed us to learn about all the modifications cybercriminals had introduced into the latest versions of the program. Our team of analysts had also made progress: by the year’s end we had a clear insight into how the malware worked, what it comprised and what optional modules it had in its arsenal.
Most of this information came from the analysis of incidents caused by Lurk-based attacks. We were simultaneously providing technical consultancy to the law enforcement agencies investigating the activities of this gang.
It was clear that the cybercriminals were trying to counteract the changes introduced in banking and IT security. For example, once the banking software vendors stopped providing demo versions of their programs for public access, the members of the criminal group established a shell company to receive directly any updated versions of the RBS software.
Thefts declined as a result of improvements in the security of banking software, and the “auto money flow” became less effective. As far as we can judge from the data we have, in 2014 the criminal group behind Lurk seriously reduced its activity and “lived from hand to mouth”, attacking anyone they could, including ordinary users. Even if the attack could bring in no more than a few tens of thousands of rubles, they would still descend to it.
In our opinion, this was caused by economic factors: by that time, the criminal group had an extensive and extremely costly network infrastructure, so, in addition to employees’ salaries, it was necessary to pay for renting servers, VPN and other technical tools. Our estimates suggest that the network infrastructure alone cost the Lurk managers tens of thousands of dollars per month.Attempts to come back
In addition to increasing the number of “minor” attacks, the cybercriminals were trying to solve their cash flow problem by “diversifying” the business and expanding their field of activity. This included developing, maintaining and renting the Angler exploit pack (also known as XXX). Initially, this was used mainly to deliver Lurk to victims’ computers. But as the number of successful attacks started to decline, the owners began to offer smaller groups paid access to the tools.
By the way, judging by what we saw on Russian underground forums for cybercriminals, the Lurk gang had an almost legendary status. Even though many small and medium-sized groups were willing to “work” with them, they always preferred to work by themselves. So when Lurk provided other cybercriminals with access to Angler, the exploit pack became especially popular – a “product” from the top underground authority did not need advertising. In addition, the exploit pack was actually very effective, delivering a very high percentage of successful vulnerability exploitations. It didn’t take long for it to become one of the key tools on the criminal2criminal market.
As for extending the field of activity, the Lurk gang decided to focus on the customers of major Russian banks and the banks themselves, whereas previously they had chosen smaller targets.
In the second half of 2014, we spotted familiar pseudonyms of Internet users on underground forums inviting specialists to cooperate on document fraud. Early the following year, several Russian cities were swamped with announcements about fraudsters who used fake letters of attorney to re-issue SIM cards without their owners being aware of it.
The purpose of this activity was to gain access to one-time passwords sent by the bank to the user so that they could confirm their financial transaction in the online or remote banking system. The attackers exploited the fact that, in remote areas, mobile operators did not always carefully check the authenticity of the documents submitted and released new SIM cards at the request of cybercriminals. Lurk would infect a computer, collect its owner’s personal data, generate a fake letter of attorney with the help of “partners” from forums and then request a new SIM card from the network operator.
Once the cybercriminals received a new SIM card, they immediately withdrew all the money from the victim’s account and disappeared.
Although initially this scheme yielded good returns, this didn’t last long, since by then many banks had already implemented protection mechanisms to track changes in the unique SIM card number. In addition, the SIM card-based campaign forced some members of the group and their partners out into the open and this helped law enforcement agencies to find and identify suspects.
Alongside the attempts to “diversify” the business and find new cracks in the defenses of financial businesses, Lurk continued to regularly perform “minor thefts” using the proven method of auto money flow. However, the cybercriminals were already planning to earn their main money elsewise.New “specialists”
In February 2015, Kaspersky Lab’s Global Research and Analysis Team (GReAT) released its research into the Carbanak campaign targeting financial institutions. Carbanak’s key feature, which distinguished it from “classical” financial cybercriminals, was the participation of professionals in the Carbanak team, providing deep knowledge of the target bank’s IT infrastructure, its daily routine and the employees who had access to the software used to conduct financial transactions. Before any attack, Carbanak carefully studied the target, searched for weak points and then, at a certain moment in time, committed the theft in no more than a few hours. As it turned out, Carbanak was not the only group applying this method of attack. In 2015, the Lurk team hired similar experts.
How the Carbanak group operated.
We realized this when we found incidents that resembled Carbanak in style, but did not use any of its tools. This was Lurk. The Lurk malware was used as a reliable “back door” to the infrastructure of the attacked organization rather than as a tool to steal money. Although the functionality that had previously allowed for the near-automatic theft of millions no longer worked, in terms of its secrecy Lurk was still an extremely dangerous and professionally developed piece of malware.
However, despite its attempts to develop new types of attacks, Lurk’s days were numbered. Thefts continued until the spring of 2016. But, either because of an unshakable confidence in their own impunity or because of apathy, day-by-day the cybercriminals were paying less attention to the anonymity of their actions. They became especially careless when cashing money: according to our incident analysis, during the last stage of their activity, the cybercriminals used just a few shell companies to deposit the stolen money. But none of that mattered any more as both we and the police had collected enough material to arrest suspected group members, which happened early in June this year.No one on the Internet knows you are a cybercriminal?
My personal experience of the Lurk investigation made me think that the members of this group were convinced they would never be caught. They had grounds to be that presumptuous: they were very thorough in concealing the traces of their illegal activity, and generally tried to plan the details of their actions with care. However, like all people, they made mistakes. These errors accumulated over the years and eventually made it possible to put a stop to their activity. In other words, although it is easier to hide evidence on the Internet, some traces cannot be hidden, and eventually a professional team of investigators will find a way to read and understand them.
Lurk is neither the first nor the last example to prove this. The infamous banking Trojan SpyEye was used to steal money between 2009 and 2011. Its alleged creator was arrested 2013, and convicted in 2014.
The first attacks involving the banking Trojan Carberp began in 2010; the members of the group suspected of creating and distributing this Trojan were arrested in 2012 and convicted in 2014. The list goes on.
The history of these and other cybercriminal groups spans the time when everyone (and members of the groups in particular) believed that they were invulnerable and the police could do nothing. The results have proved them wrong.
Unfortunately, Lurk is not the last group of cybercriminals attacking companies for financial gain. We know about some other groups targeting organizations in Russia and abroad. For these reasons, we recommend that all organizations do the following:
- If your organization was attacked by hackers, immediately call the police and involve experts in digital forensics. The earlier you apply to the police, the more evidence the forensics will able to collect, and the more information the law enforcement officers will have to catch the criminals.
- Apply strict IT security policies on terminals from which financial transactions are made and for employees working with them.
- Teach all employees who have access to the corporate network the rules of safe online behavior.
Compliance with these rules will not completely eliminate the risk of financial attacks but will make it harder for fraudsters and significantly increase the probability of their making a mistake while trying to overcome these difficulties. And this will help law enforcement agencies and IT security experts in their work.P.S.: why does it take so long?
Law enforcement agencies and IT security experts are often accused of inactivity, allowing hackers to remain at large and evade punishment despite the enormous damage caused to the victims.
The story of Lurk proves the opposite. In addition, it gives some idea of the amount of work that has to be done to obtain enough evidence to arrest and prosecute suspects. Unfortunately, the rules of the “game” are not the same for all participants: the Lurk group used a professional approach to organizing a cybercriminal enterprise, but, for obvious reasons, did not find it necessary to abide by the law. As we work with law enforcement, we must respect the law. This can be a long process, primarily because of the large number of “paper” procedures and restrictions that the law imposes on the types of information we as a commercial organization can work with.
Our cooperation with law enforcement in investigating the activity of this group can be described as a multi-stage data exchange. We provided the intermediate results of our work to the police officers; they studied them to understand if the results of our investigation matched the results of their research. Then we got back our data “enriched” with the information from the law enforcement agencies. Of course, it was not all the information they could find; but it was the part which, by law, we had the right to work with. This process was repeated many times until we finally we got a complete picture of Lurk activity. However, that was not the end of the case.
A large part of our work with law enforcement agencies was devoted to “translating” the information we could get from “technical” into “legal” language. This ensured that the results of our investigation could be described in such a way that they were clear to the judge. This is a complicated and laborious process, but it is the only way to bring to justice the perpetrators of cybercrimes.
While ransomware is a global threat, every now and then we see a variant that targets one specific region. For example, the Coinvault malware had many infections in the Netherlands, because the authors posted malicious software on Usenet and Dutch people are particular fond of downloading things over Usenet. Another example is the recent Shade campaign, which targets mostly Russia and CIS.
Today we can add a new one to the list: Wildfire.Infection vector
Wildfire spreads through well-crafted spam e-mails. A typical spam e-mail mentions that a transport company failed to deliver a package. In order to schedule a new delivery the receiver is asked to make a new appointment, for which a form has to be filled in, which has to be downloaded from the website of the transport company.
Three things stand out here. First, the attackers registered a Dutch domain name, something we do not see very often. Second, the e-mail is written in flawless Dutch. And thirdly, they actually put the address of the targeted company in the e-mail. This is something we do not see very often and makes it for the average user difficult to see that this is not a benign e-mail.
However, when we look at who registered the domain name, we immediately see that something is suspicious:
The registration date (registered a few days before the spam campaign started), as well as the administrative contact person seem to be very suspicious.The Word document
After the user downloaded and opened the Word document, the following screen is shown:
Apparently the document has some macros, containing pieces of English text, which clearly show the intent of the attackers (actually it is the lyrics of the famous Pink Floyd song Money), but also has several variables in the Polish language.
The macros download and execute the actual Wildfire ransomware which consists in the case we analyzed of the following three files:
The exe file is an obfuscated .net executable that depends on the other two files. This is exactly similar to the Zyklon ransomware that also consists of three files. Another similarity is that, according to some sources (http://www.bleepingcomputer.com/forums/t/611342/zyklon-locker-gnl-help-topic-locked-and-unlock-files-instructionshtml/, http://www.bleepingcomputer.com/forums/t/618641/wildfire-locker-help-topic-how-to-unlock-files-readme-6de99ef7c7-wflx/), Wildfire, GNLocker and Zyklon mainly target the Netherlands. In addition, the ransom notes of Wildfire and Zyklon look quite similar. Also note that Wildfire and Zyklon increase the amount you have to pay three-fold if you don’t pay within the specified amount of time.
Anyway, back to Wildfire. The binary is obfuscated, meaning that when there is no deobfuscator available reversing and analyzing it can take a lot of time. Therefore we decided to run it and see what happens. Just as we hoped, this made things a bit easier, because after a while Usiyykssl.exe launched Regasm.exe, and when we looked into the memory of Regasm.exe, we clearly saw that some malicious code had been injected into it.
Dumping it gave us the binary of the actual Wildfire malware. Unfortunately for us, this binary is also obfuscated, this time with Confuserex 0.6.0. Even though it is possible to deobfuscate binaries obfuscated with Confuserex, we decided to skip that for now. Why? Well it takes a bit of time, and because by working together with the police on this case, we had something much better in our hands: The botnetpanel code!Inside the botnetpanel code
When you are infected with Wildfire, the malware calls home to the C2 server where information such as the IP, username, rid and country are stored. The botnetpanel then checks whether the country is one of the blacklisted countries (Russia, Ukraine, Belarus, Latvia, Estonia and Moldova). It also checks whether the “rid” exists within a statically defined array (we therefore expect the rid to be an affiliate ID).
If the rid is not found, or you live in one of the blacklisted countries, the malware terminates and you won’t get infected.
Each time the malware calls home, a new key is generated and added to the existing list of keys. The same victim can thus have multiple keys. Finally the botnetpanel returns the bitcoin address to which the victim should pay, and the cryptographic key with which the files on the victim’s computer are encrypted. We don’t quite understand why a victim can have multiple keys, especially since the victim only has one bitcoin address.
Also interesting is the encryption scheme. It uses AES in CBC mode but the key and the IV are both derived from the same key. This doesn’t add much security and defeats the sole purpose of having an IV in the first place.
Even though Wildfire is a local threat, it still shows that ransomware is effective and evolving. In less than a month we observed more than 5700 infections and 236 users paid a total amount of almost 70.000 euro . This is also due to the fact that the spam e-mails are getting better and better.
We therefore advise users to:
- Be very suspicious when opening e-mails;
- Don’t enable Word macro’s;
- Always keep your software up-to-date;
- Turn on Windows file extensions;
- Create offline backups (or online backups with unlimited revisions);
- Turn on the behavioral analyzer of your AV.
A decryption tool for Wildfire can be downloaded from the nomoreransom.org website.
P.S. the attackers agree with us on some points:
The telecommunications industry keeps the world connected. Telecoms providers build, operate and manage the complex network infrastructures used for voice and data transmission – and they communicate and store vast amounts of sensitive data. This makes them a top target for cyber-attack.
According to PwC’s Global State of Information Security, 2016, IT security incidents in the telecoms sector increased 45% in 2015 compared to the year before. Telecoms providers need to arm themselves against this growing risk.
In this intelligence report, we cover the main IT security threats facing the telecommunications industry and illustrate these with recent examples.
Our insight draws on a range of sources. These include:
- The latest telecoms security research by Kaspersky Lab experts.
- Kaspersky Lab monitoring systems, such as the cloud antivirus platform, Kaspersky Security Network (KSN), our botnet tracking system and multiple other internal systems including those used to detect and track sophisticated targeted (advanced persistent threat, APT) attacks and the corresponding malware.
- Underground forums and communities.
- Centralized, specialized security monitoring systems (such as Shodan).
- Threat bulletins and attack reports.
- Newsfeed aggregation and analysis tools.
Threat intelligence is now a vital weapon in the fight against cyber-attack. We hope this report will help telecoms providers to better understand the cyber-risk landscape so that they can develop their security strategies accordingly.
We can provide more detailed sector and company-specific intelligence on these and other threats. For more information on our Threat Intelligence Reporting services please email email@example.com.Executive summary
Telecommunications providers are under fire from two sides: they face direct attacks from cybercriminals intent on breaching their organization and network operations, and indirect attacks from those in pursuit of their subscribers. The top threats currently targeting each of these frontlines feature many classic attack vectors, but with a new twist in terms of complexity or scale that place new demands on telecoms companies.
These threats include:
- Distributed Denial of Service (DDoS) attacks. DDoS attacks continue to increase in power and scale and, according to the 2016 Data Breach Investigations Report, the telecommunications sector is hit harder than any other. Kaspersky Lab’s research reveals that in Q2, 2016, the longest DDoS attack lasted for 291 hours (or 12.1 days) – significantly longer than the previous quarter’s maximum (8.2 days), with vulnerable IoT devices increasingly used in botnets. Direct DDoS attacks can reduce network capacity, degrade performance, increase traffic exchange costs, disrupt service availability and even bring down Internet access if ISPs are hit. They can be a cover for a deeper, more damaging secondary attack, or a route into a key enterprise subscriber or large-scale ransomeware attack.
- The exploitation of vulnerabilities in network and consumer devices. Our intelligence shows that vulnerabilities in network devices, consumer or business femtocells, USBs and routers, as well as root exploits for Android phones, all provide new channels for attacks – involving malware and technologies that individuals, organisations and even basic antivirus solutions cannot always easily remove.
- Compromising subscribers with social engineering, phishing or malware. These classic techniques remain popular and can easily be mastered by entry-level cybercriminals, although 2016 sees changes in how more sophisticated attackers conduct their campaigns. Growing numbers of cyber-attackers now combine data sets from different sources, including open sources, to build up detailed pictures of potential targets for blackmail and social engineering purposes.
- Insider threat is growing. Detailed profiles of targets are also used to recruit insiders to help perpetrate cybercrime. Some insiders help voluntarily, others are cooerced through blackmail. Insiders from cellular service providers are recruited mainly to provide access to data, while staff working for Internet service providers are chosen to support network mapping and man-in-the-middle attacks.
Other threats facing telecommunications companies include targeted attacks; poorly configured access controls, particularly where interfaces are publicly available to any Internet user; inadequate security for 2G/3G communications; and the risk of telecoms providers being drawn into unrelated attacks that exploit telecoms resources, and suffering collateral damage as a result.Typical threats targeting telecoms Overview
We can divide the main threats facing the telecommunications industry into two, interrelated, categories:
- Threats targeting telecommunication companies directly. These include DDoS attacks, targeted attacks (APT campaigns), network device vulnerabilities and human-related threats like insider access, social engineering and the risk of allowing third parties to access information.
- Threats targeting subscribers of telecoms services – particularly the customers of cellular service providers (CSPs) and Internet service providers (ISPs). These include malware for mobile devices, subscriber data harvesting, end-user device vulnerabilities, and more.
DDoS (distributed denial of service) attacks remain a serious threat to telecoms providers around the world as attackers discover ever more ways of boosting the power and scale of attacks. Kaspersky Lab’s DDoS intelligence report for Q2, 2016 notes that websites in 70 countries were targeted with attacks. By far the most affected country was China, with South Korea and the US also among the leaders. 70.2% of all detected attacks were launched from Linux botnets, with cybercriminals paying close attention to financial institutions working with cryptocurrency. Another trend observed in Q2 was the use of vulnerable IoT devices in botnets to launch DDoS attacks.
The telecommunications sector is particularly vulernable to DDoS attacks. According to the 2016 Data Breach Investigations Report, the telecommunications sector was hit around twice as hard as the second placed sector (financial exchanges), with a median DDoS packet count of 4.61 million packets per second (compared to 2.4 Mpps for exchanges.)
The impact of a DDoS attack should not be underestimated. Direct attacks can reduce network capacity, degrade performance, increase traffic exchange costs, disrupt service availability and even bring down Internet access if ISPs are affected. With a growing number of connected devices and systems supporting mission-critical applications in areas such as healthcare and transport, unexpected downtime could be life threatening.
Further, DDoS attacks can be a cover for a deeper, more damaging secondary attack, or a route into a key enterprise subscriber or large-scale ransomeware attack.
A good example of the first is the 2015 cyber-attack on the UK telecoms company, TalkTalk. The hack, alledgedly perpetrated by a couple of teenagers, resulted in the loss of around 1.2 million customers’ email addresses, names and phone numbers, as well as many thousands of customer dates of birth and financial information – all ideal for use in financially-motivated social engineering campaigns. The forensic investigation revealed that the hackers had used a smokescreen DDoS attack to conceal their main activities.
DDoS attacks are also evolving. 2015 saw attackers amplify the power of DDoS attacks by turning them into DrDoS (Distributed reflection Denial of Service) attacks through the use of standard network protocols like NTP, RIPv1, NetBIOS (Network Basic Input/Output System) and BGP (Border Gateway Patrol). Another approach that is becoming more commonplace is the compromise of end-user routers via network-scanning malware and firmware vulnerabilities. Today’s faster mobile data transfer speeds and the growing adoption of 4G are also making smartphone-based botnets more useful for implementing DDoS attacks.
The worrying thing is that even inexperienced attackers can organize quite an effective DDoS campaign using such techniques.Targeted attacks
The core infrastructure of a telecommunications company is a highly desirable target for cybercriminals, but gaining access is extremely difficult. Breaking into the core requires a deep knowledge of GSM architecture, rarely seen except among the most skilled and resourced cybercriminals. Such individuals can generally be found working for advanced, international APT groups and nation-state attackers, entities that have a powerful interest in obtaining access to the inner networks of telecommunication companies. This is because compromised network devices are harder to detect by security systems and they offer more ways to control internal operations than can be achieved through simple server/workstation infiltration.
Once inside the core infrastructure, attackers can easily intercept calls and data, and control, track and impersonate subscibers.
Other APTs with telecommunications on their radar
The Regin APT campaign, discovered in 2014, remains of the most sophisticated ever seen and has the ability to infiltrate GSM networks, while the Turla group, has developed the ability to hijack satellite-based Internet links as part of it’s Command & Control process, successfully obscuring its actual location.
Others, such as Dark Hotel and a new cyber-espionage threat actor likely to be of Chinese origin, exploit telecoms networks in their targeted campaigns. In these cases, the telecoms providers often suffer collateral damage even though they are not directly related to the attack. Further details on these can be found on Kaspersky Lab’s expert Securelist blog or through a subscription to the Kaspersky APT Threat Intelligence Reporting service.Unaddressed software vulnerabilities
Despite all the high profile hacks and embarrassing data leaks of the last 12 months, attackers are still breaching telecoms defenses and making off with vast quantities of valuable, personal data. In many cases, attackers are exploiting new or under-protected vulnerabilities. For example, in 2015, two members of the hacker group, Linker Squad gained access to Orange Spain through a company website vulnerable to a simple SQL injection, and stole 10 million items of customer and employee data.
SQL injection vulnerability on Orange Spain web siteThe impact of service misconfiguration
In many cases, the hardware used by by the telecommunications industry carries configuration interfaces that can be accessed openly via HTTP, SSH, FTP or telnet. This means that if the firewall is not configured correctly, the hardware in question becomes an easy target for unauthorized access.
The risk presented by publicly exposed GTP/GRX (GPRS Tunneling Protocol/GPRS Roaming Exchange) ports on devices provides a good example of this.
As CSPs encrypt the GPRS traffic between the devices and the Serving GPRS Support Node (SGSN), it is difficult to intercept and decrypt the transferred data. However, an attacker can bypass this restriction by searching on Shodan.io for devices with open GTP ports, connecting to them and then encapsulating GTP control packets into the created tunnel.
Table 1. Top 10 countries with GTP/GRX ports exposed to Internet access# Country Number of GTP/GRX 1 China 52.698 2 Turkey 8.591 3 United States of America 6.403 4 Canada 5.807 5 Belgium 5.129 6 Colombia 2.939 7 Poland 2.842 8 Morocco 1.585 9 Jamaica 862 10 United Arab Emirates 808
The Border Gateway Protocol (BGP) is the routing protocol used to make decisions on routing between autonomous systems. Acceptance and propagation of routing information coming from other peers can allow an attacker to implement man-in-the-middle (MITM) attacks or cause denial of service. Any route that is advertised by a neighboring BGP speaker is merged in the routing database and propagated to all the other BGP peers.
Table 2. Top five countries with BGP protocol exposed to Internet access# Country Number of devices
(end of 2015) 1 Republic of Korea 16.209 2 India 8.693 3 United States of America 8.111 4 Italy 2.909 5 Russian Federation 2.050
An example of such an attack took place in March 2015, when Internet traffic for 167 important British Telecom customers, including a UK defense contractor that helps to deliver the country’s nuclear warhead program, was illegally diverted to servers in Ukraine before being passed along to its final destinations.
To avoid probable attacks against BGP from unauthorized remote malefactors, we recommend that companies provide network filtering, allowing only a limited number of authorized peers to connect to BGP services. To protect against malicious re-routing and hijacking initiated through authorized autonomous systems we recommend that they monitor anomalies in BGP communications (this can be done through specialized software solutions or by subscribing to alerts from vendors providing this kind of monitoring.)Vulnerabilities in network devices
Routers and other network devices are also primary targets for attacks against telecommunications companies.
In September 2015, FireEye researchers revealed the router malware “SYNful knock”, a combination of leaked privilege (root) credentials and a way of replacing device firmware that targets Cisco 1841, 2811 and 3825 routers (see Cisco advisory here).
Put simply, SYNful knock is a modified device firmware image with backdoor access that can replace the original operating system if the attacker has managed to obtain privileged access to the device or can physically connect to it.
SYNful is not a pure software vulnerability, but a combination of leaked privileged credentials combined with a certain way of replacing device firmware. Still, it is a dangerous way of compromising an organization’s IT infrastructure.
SYNful knock backdoor sign-in credentials request
Worldwide distribution of devices with the SYNful knock backdoor
The latest information on the number of potentially compromised devices is available through the link https://synfulscan.shadowserver.org/stats/.
A second Cisco vulnerability, CVE-2015-6389 enables attackers to access some sensitive data, such as the password file, system logs, and Cisco PCA database information, and to modify data, run internal executables and potentially make the system unstable or inaccessible. Cisco Prime Collaboration Assurance Software releases prior to 11.0 are vulnerable. Follow this Cisco bulletin for remediation actions.
For further information on Cisco fixes for its devices see https://threatpost.com/cisco-warning-of-vulnerabilities-in-routers-data-center-platforms/115609.
Juniper, another network device manufacturer has been found to carry vulnerabilities in its operating system for its NetScreen VPN appliances, enabling third-party access to network traffic. The issue was reported by the vendor in the security advisory JSA10713 on December 18th, 2015, along with the release of the patch.
It appears that the additional code with hardcoded password was planted in the source code in late 2013. The backdoor allows any user to log in with administrator privileges using hard-coded password “<<< %s(un=’%s’) = %u”.This vulnerability has been identified as CVE-2015-7755 and is considered highly critical.
Top countries where ScreenOS devices are used are the Netherlands, the United States, China, Italy and Mexico.
Juniper ScreenOS-powered devices worldwide
Another Juniper backdoor, CVE-2015-7756, affects ScreenOS 6.2.0r15 through 6.2.0r18 and 6.3.0r12 through 6.3.0r20 and allows a third party to monitor traffic inside VPN connections due to security flaws in the Dual_EC PRNG algorithm for random number generation.
To protect the organization from misconfiguration and network device vulnerabilitiy, Kaspresky Lab recommendats that companies pay close attention to vulnerabilities in the network services of telecommunication equipment, establish effective vulnerability and configuration management processes, and regularly perform security assessments, including penetration testing for different types of attackers (a remote intruder, a subscriber, a contractor, etc.).Malicious insiders
Even if you consider your critical systems and devices protected and safe, it is difficult to fully control some attack vectors. People rank at the very top of this list. Their motivations are often hard to predict and anticipate, ranging from a desire for financial gain to disaffection, coercion and simple carelessness.
While insider-assisted attacks are uncommon, the impact of such attacks can be devastating as they provide a direct route to the most valuable information.
Examples of insider attacks in recent years include:
- A rogue telecoms employee leaking 70 million prison inmate calls, many breaching client-attorney privilege.
- An SMS center support engineer who had intercepted messages containing OTP (One-Time Passwords) for the two-step authentication required to login to customer accounts at a popular fintech company. The engineer was found to be freely offering his services on a popular DarkNet forum.
For attackers, infiltrating the networks of ISPs and CSPs requires a certain level of experience – and it is often cheaper and easier to stroll across the perimeter with the help of a hired or blackmailed insider. Cybercriminals generally recruit insiders through two approaches: enticing or coercing individual employees with relevant skills, or trawling around underground message boards looking for an appropriate employee or former employee.
Employees of cellular service providers are in demand for fast track access to subscriber and company data or SIM card duplication/illegal reissuing, while staff working for Internet service providers are needed for network mapping and man-in-the-middle attacks.
A particularly promising and successful attack vector for recruiting an insider for malicious intrusion is blackmail.
Data breaches, such as the 2015 Ashley Madison leak reveal information that attackers can compare with other publically available information to track down where people work and compromise them accordingly. Very often, these leaked databases contain corporate email addresses, including those of telecommunication companies.
Further information on the emerging attack vectors based on the harvesting of Open Source Intelligence (OSINT) can be obtained using Kaspersky Lab’s customer-specific Intelligence Reporting services.Threats targeting CSP/ISP subscribers Overview
Attacks targeting the customers of cloud and Internet service providers remain a key area of interest for cybercriminals. We’ve revealed a number of malware activities and attack techniques based on internal information and incidents that were caught in our scope. As a result of analyzing this data the following main threats were identified:
- Obtaining subscribers’ credentials. This is growing in appeal as consumers and businesses undertake ever more activity online and particularly on mobile. Further, security levels are often intentionally lowered on mobile devices in favor of usability, making mobile attacks even more attractive to criminals.
- Compromising subscribers’ devices. The number of mobile malware infections is on the rise, as is the sophistication and functionality of the malware. Experienced and skilled programmers are now focusing much of their attention on mobile – looking to exploit payment services as well as low-valued assets like compromised Instagram or Uber accounts, collecting every piece of data from the infected devices.
- Compromising small-scale telecoms cells used by consumers and businesses. Vulnerabilities in CSP-provided femtocells allow criminals to compromise the cells and even gain access to the entire cloud provider’s network.
- Successful Proof-Of-Concept attacks on USIM cards. Recent research shows that the cryptography of 3G/4G USIM cards is no longer unbreakable. Successful attacks allow SIM card cloning, call spoofing and the interception of SMS.
Social engineering and phishing remain popular activities and they continues to evolve and improve, targeting unaware or poorly aware subscribers and telecoms employees.
The attackers exploit trust and naiivity. In 2015, the TeamHans hacker group penetrated one of Canada’s biggest communications groups, Rogers, simply by repeatedly contacting IT support and impersonating mid-ranking employees, in order to build up enough personal information to gain access to the employee’s desktop. The attack provided hackers with access to contracts with corporate customers, sensitive corporate e-mails, corporate employee IDs, documents, and more.
Both social engineering and phishing approaches are worryingly successful. The Data Breach Investigations Report 2016 found that 30% of phishing emails were opened, and that 12% clicked on the malicious attachment – with the entire process taking, on average, just 1 minute and 40 seconds.
Social engineers and phishers also use multiple ways for increasing the likeness of authenticity in their attacks, enriching their data with leaked profiles, or successfully impersonating employees or contractors. Recently criminals have successfully stolen tens of thousands of euros from dozens of people across Germany after finding a way around systems that text a code to confirm transactions to online banking users. After infecting their victims with banking malware and obtaining their phone numbers, they called the CSP’s support and, impersonating a retail shop, asked for a new SIM card to be activated, thus gaining access to OTP (One Time Passwords) or “mTan’s” used for two-factor authentication in online banking.
Kaspersky Lab recommends that telecommunications providers implement notification services for financial organizations that alert them when a subscriber’s SIM card has been changed or when personal data is modified.
Some CSPs have also implemented a threat exchange service to inform financial industry members when a subscriber’s phone is likely to have been infected with malware.Vulnerable kit
USBs, modems and portable Wi-Fi routers remain high-risk assets for subscribers, and we continue to discover multiple vulnerabilities in their firmware and user interfaces. These include:
- Vulnerabilities in web interfaces designed to help consumers configure their devices. These can be modified to trick a user into visiting a specially crafted page.
- Vulnerabilities that result from insufficient authentication. These can allow for the modification of device settings (like DNS server addresses), and the interception, sending and receiving of SMS messages, or USSD requests, by exploiting different XSS and CSRF vulnerabilities.
- RCE (Remote Code Execution) vulnerabilities based on different variants of embedded Linux that can enable firmware modification and even a complete remote compromise.
Built-in “service” backdoor allowing no-authentication access to device settings
Examples of these kind of vulnerabilities were demonstrated in research by Timur Yunusov from the SCADAStrangeLove team. The author assessed a number of 3G/4G routers from ZTE, Huawei, Gemtek and Quanta. He has reported a number of serious vulnerabilities:
- Remote Code Execution from web scripts.
- Arbitrary device firmware modification due to insufficient consistency checks.
- Cross Site Request Forgert and Cross Site Scripting attacks.
All these vectors can be used by an external attacker for the following scenarios:
- Infecting a subscriber’s computer via PowerShell code or badUSB attack.
- Traffic modification and interception.
- Subscriber account access and device settings modification.
- Revealing subscriber location.
- Using device firmware modification for APT attack persistence.
Most of these issues exist due to web interface vulnerabilities (like insufficient input validation or CSRF) or modifications made by the vendor during the process of branding its devices for a specific telecommunications company.The risk of local cells
Femtocells, which are essentially a personal NodeB with an IP network connection, are growing in popularity as an easy way to improve signal coverage inside buildings. Small business customers often receive them from their CSPs. However, unlike core systems, they are not always submitted to suitably thorough security audits.
Femtocell connection map
Over the last year, our researchers have found a number of serious vulnerabilities in such devices that could allow an attacker to gain complete control over them. Compromising a femtocell can lead to call interception, service abuse and even illegal access to the CSP’s internal network.
At the moment, a successful attack on a femtocell requires a certain level of engineering experience, so risks remain low – but this is likely to change in the future.USIM card vulnerabilities
Research presented at BlackHat USA in 2015 revealed successful attacks on USIM card security. USIMs had previously been considered unbreakable thanks to the AES-based MILENAGE algorithm used for authentication. The reseachers conducted differential power analysis for the encryption key and secrets extraction that allowed them to clone the new generation of 3G/4G SIM cards from different manufacturers.
Right byte guess peak on differential power analysis graphConclusion
Telecommunications is a critical infrastructure and needs to be protected accordingly. The threat landscape shows that vulnerabilities exist on many levels: hardware, software and human, and that attacks can come from many directions. Telecoms providers need to start regarding security as a process – one that encompasses threat prediction, prevention, detection, response and investigation.
A comprehensive, multi-layered security solution is a key component of this, but it is not enough on its own. It needs to be complemented by collaboration, employee education and shared intelligence. Many telecommunications companies already have agreements in place to share network capability and capacity in the case of disruption, and now is the time to start reaping the benefit of shared intelligence.
Our Threat Intelligence Reporting services can provide customer-specific insight into the threats facing your organization. If you’ve ever wondered what your business looks like to an attacker, now’s the time to find out. Contact us at firstname.lastname@example.org
Crooks are always creating new ways to improve the malware they use to target bank accounts, and now Brazilian bad guys have made an important addition to their arsenal: the use of PowerShell. Brazil is the most infected country worldwide when it comes to banking Trojans, according to our Q1 2016 report, and the quality of the malware is evolving dramatically. We found Trojan-Proxy.PowerShell.Agent.a in the wild a few days ago, marking a new achievement by Brazil’s cybercriminals.
The malware is distributed using a malicious email campaign disguised as a receipt from a mobile operator with a malicious .PIF file. After the file is executed it changes the proxy configuration in Internet Explorer to a malicious proxy server that redirects connections to phishing pages for Brazilian banks. It’s the same technique used by malicious PACs that we described in 2013, but this time no PACs are used; the changes in the system are made using a PowerShell script. As Windows 7 and newer OS versions are now the most popular in Brazil, the malware will not face a problem running on victims’ computers.
The malware has no C&C communication. After execution it spawned the process “powershell.exe” with the command line “-ExecutionPolicy Bypass -File %TEMP%\599D.tmp\599E.ps1” aiming to bypass PowerShell execution policies. The .ps1 file in the temp folder uses random names. It’s a base64 encoded script capable of making changes in the system.
After some deobfuscation we can see the goal of the script: to change the Internet Settings key and enable a proxy server on it:
And this is the result in the browser of the victim – a small change in the proxy settings:
This change will not only affect IE but all other browsers installed in the system as well, as they tend to use the same proxy configuration set on IE. The proxy domains used in the attack are listed below. All of them use dynamic DNS services and their goal is to redirect all traffic to a server located in the Netherlands (22.214.171.124), where there are several phishing pages for Brazilian banks:
The malware also has other features of interest: it checks for the language of the OS and aborts if it’s not PTBR, a clever trick to avoid infecting Windows versions in languages other than Brazilian Portuguese.
To protect a network against malware that uses PowerShell, it is important to modify its execution, using administrative templates that only allow signed scripts. We are sure this is the first of many that Brazil’s bad guys will code.
Hash of the malware: cancelamento.pif -> MD5: 9419e7cd60487532313a43559b195cb0
Although the second quarter of 2016 has only just finished, it’s safe to say that this is already the year of ransomware Trojans. By the end of Q2 there was still a large number of emails with malicious attachments, most of which download ransomware in one way or other to a victim’s computer. However, in the period between 1 June and 21 June the proportion of these emails decreased dramatically.
The majority of malicious attachments were distributed in ZIP archives. The decline can therefore be clearly seen in the following graph showing spam with ZIP attachments that arrived in our traps:
Number of emails with malicious ZIP archives, Q2 2016
In addition to the decline, June saw another interesting feature: this sort of spam was not sent out on Saturdays or Sundays.
The same situation could be observed in KSN: the number of email antivirus detections dropped sharply on 1 June and grew on 22 June.
Number of email antivirus detections by day, Q2 2016
This decline was caused by a temporary lull in activity by the Necurs botnet, which is mostly used to distribute this type of malicious spam. After the botnet resumed its activity, the spam email template changed, and the malicious attachments became even more sophisticated.
For example, some emails (see the screenshot above) contained an attachment with a Trojan downloader. When run, it downloaded Trojan-Ransom.Win32.Locky.agn, which encrypts the data on a victim’s computer and demands a ransom, to be paid in bitcoin.Obfuscation
The second quarter saw spammers continue to mask links using various Unicode ranges designed for specific purposes. This tactic became especially popular in 2015, and is still widely used by spammers.
The link in this example looks like this:
If you transfer the domain from UTF-8 into the more familiar HTML, it becomes . The characters, which look quite ordinary, in fact belong to the Mathematical Alphanumeric Symbols UTF range used in highly specific mathematical formulas, and are not intended for use in plain text or hyperlinks. The dot in the domain is also unusual: it is the fullwidth full stop used in hieroglyphic languages. The rest of the hyperlink, as well as the rest of the text in these spam messages, is written using the Latin alphabet.Spam in APT attacks
In Q2, we came across a number of APT attacks in the corporate sector. Emails were made to look as if they came from representatives of the targeted company, and contained a request to immediately transfer money to a specific account. The text was fairly plausible and hinted at a personal acquaintance and previous communication. In some cases, the emails included the logo of the attacked company. All the messages conveyed a sense of urgency (“ASAP”, “urgent”, “must be completed today”) – scammers often use this trick in an attempt to catch people off guard, so that they act rather than think.
Below is an example:
How are you doing! Are you available at the office? I need you to process an overdue payment that needs to be paid today.
The emails were sent selectively – to individual employees, usually connected to the finance department. The knowledge shown by the scammers suggests the attack was carefully prepared.
The most suspicious aspect of the attack was the domain used in the ‘From’ field – myfirm.moby – that differed from the corporate one. Perhaps the attackers hope that some email clients only show the sender’s name by default, while concealing the address.
It is not that difficult to write any domain in the ‘From’ field, and in the future we can expect more well-prepared attacks.Sporting events in spam
Spam mailings exploiting real-life events have long become an integral part of junk email. Sporting events are not as popular among spammers as political events, although their use is increasing with every year. There is a continuous stream of emails mentioning various political figures, while sport-related spam messages usually only appear in the run-up to an event. However, we have noticed that mass mailings can now be launched long before an event starts. For instance, emails exploiting the Olympic Games in Brazil were discovered over a year ago, in the second quarter of 2015. The majority of them were fraudulent emails designed to trick recipients and steal their personal information and money.
The classic scenario involves false notifications about lottery wins related to 2016 Olympics. The messages claim that the lottery was held by the official organizers of the games and the recipient was selected at random from millions of addresses. In order to claim the cash, the recipient has to reply to the email and provide some personal information.
The text of the message was often contained in an attached file (.pdf, .doc, .jpg), while the body of the message only displayed a short text prompting the recipient to open the attachment.
There were also more traditional messages where the spammer text was included directly in the body of the message.
In addition to fraudulent messages, advertising spam was also sent out.
Unlike the Olympics, football tournaments have long been used by scammers to grab people’s attention to their spam. Q2 2016 saw the long-awaited UEFA European Championship, and in the run-up to the tournament spam traffic included fake notifications of lottery wins. The content was no different from that dedicated to the Olympic Games, and the emails also contained attachments explaining why the message was sent.
The football theme was also exploited by ‘Nigerian’ scammers. They sent out emails supposedly on behalf of the former FIFA president, and used the infamous corruption scandal associated with his name to make their messages look more realistic. They believed that a fabricated story about how Sepp Blatter had supposedly received money and secretly transferred it to an account in a European bank would not arouse suspicion. In return for keeping the money in their bank accounts, the recipients were promised a 40% cut of the total sum.
In order to convince recipients that the message was genuine, the authors even went to the trouble of using the correct name and domain in the ‘From’ field.US politicians in spam
The presidential election campaign is now in full swing in the United States and the nominees and their entourages are under close media scrutiny. Of course, spammers couldn’t resist using the names of high-profile politicians in their advertising and fraudulent emails. For example, numerous ‘Nigerian’ letters were sent in the name of current president Barack Obama and his wife Michelle. In their ‘official’ emails, the ‘President’ and the ‘First lady’ assured the recipient that a bank card or a check for a very large sum of money had already been issued in their name. The only thing the recipient had to do was complete some formalities, and the money would be delivered shortly afterwards. In order to get the instructions from the White House the recipient had to send some personal information, including their email address and the password for their email account, as well as detailed passport information to spoofed email addresses.
Another politician whose name regularly cropped up in spam was Donald Trump, one of the contenders for the US presidency. Spammers offered a unique Trump technique for earning money online: anyone who wanted to know how to get rich, had to click a link in the emails which were designed to look like news reports from CNN and Fox News.
The links led to fake news sites also in the style of major media outlets and news networks. The sites contained a story about a simple method for earning money – the publication of links, which is basically another kind of spam distribution. In order to participate in the program, a user had to register by providing their phone number and email address.Statistics Proportion of spam in email traffic
Percentage of spam in global email traffic, Q2 2016
The largest percentage of spam in the second quarter – 59.46% – was registered in May and was 3 p.p. more than in April. The average percentage of spam in global email traffic for Q2 amounted to 57.25%.Sources of spam by country
Sources of spam by country, Q2 2016
In Q2 2016, the biggest three sources of spam remained the same as in the previous quarter – the US (10.79%), Vietnam (10.10%) and India (10.01%). However, the figures for each country changed: the gap between them narrowed to within a single percentage point.
China (6.52%) moved up to fourth with an increase of 1.43 p. p. compared to Q1. Mexico (4.55%) came fifth, followed by Russia (4.07%) and France (3.60%). Brazil (3.28%), which was fourth in the previous quarter, lost 2.2 p.p. and dropped to eighth place. Germany (2.97%) and Turkey (2.30%) completed the TOP 10.Spam email size
Breakdown of spam emails by size, Q1 and Q2 2016
Traditionally, the most commonly distributed emails are very small – up to 2 KB (72.26%), although the proportion of these emails dropped by 9.6 p.p. compared to the previous quarter. Meanwhile, the share of emails sized 10-20 KB increased by 6.76 p.p. The other categories saw minimal changes.Malicious email attachments
Currently, the majority of malicious programs are detected proactively by automatic means, which makes it very difficult to gather statistics on specific malware modifications. So we have decided to turn to the more informative statistics of the TOP 10 malware families.TOP 10 malware families
The three most popular malware families remained unchanged from the previous quarter – Trojan-Downloader.JS.Agent (10.45%), Trojan-Downloader.VBS.Agent (2.16%) and Trojan-Downloader.MSWord.Agent (1.82%).
The Trojan.Win32.Bayrob family moved up to fourth place (1.68%), while the Backdoor.Win32.Androm family fell from fourth to ninth place with 0.6%.
TOP 10 malware families in Q2 2016
A newcomer to this ranking was the Trojan.Win32.Inject family (0.61%). The malicious programs from this family embed their code in the address space of other processes.
The Trojan-Spy.HTML.Fraud family (0.55%) rounded off the TOP 10 in Q2 2016.Countries targeted by malicious mailshots
Distribution of email antivirus verdicts by country, Q2 2016
Germany (14.69%) topped the ranking of countries targeted by malicious mailshots, although its share decreased 4.24 p.p. It was followed by China (13.61%) whose contribution grew 4.18 p.p. Japan (6.42%) came third after ending the previous quarter in seventh with a share of 4.29%.
Fourth place was occupied by Brazil (5.57%). Italy claimed fifth with a share of 4.9% and Russia remained in sixth (4.36%).
The US (4.06%) was the seventh most popular target of malicious mailshots. Austria (2.29%) rounded off this TOP 10.Phishing
In Q2 2016, the Anti-Phishing system was triggered 32,363,492 times on the computers of Kaspersky Lab users, which is 2.6 million less than the previous quarter. Overall, 8.7% of unique users of Kaspersky Lab products were attacked by phishers in Q2 of 2016.Geography of attacks
The country where the largest percentage of users is affected by phishing attacks was China (20.22%). In Q2 2016, the proportion of those attacked increased by 3.52 p.p.
Geography of phishing attacks*, Q2 2015
* Number of users on whose computers the Anti-Phishing system was triggered as a percentage of the total number of Kaspersky Lab users in the country
The percentage of attacked users in Brazil decreased by 2.87 p.p. and accounted for 18.63%, placing the country second in this ranking. Algeria (14.3%) came third following a 2.92 p.p. increase in its share compared to the previous quarter.
TOP 10 countries by percentage of users attacked:China 20.22% Brazil 18.63% Algeria 14.3% United Kingdom 12.95% Australia 12.77% Vietnam 11.46% Ecuador 11.14% Chile 11.08% Qatar 10.97% Maldives 10.94% Organizations under attack
The statistics on phishing targets are based on detections of Kaspersky Lab’s heuristic anti-phishing component. It is activated every time a user attempts to open a phishing page while information about it has not yet been included in Kaspersky Lab’s databases. It does not matter how the user attempts to open the page – by clicking a link in a phishing email or in a message on a social network or, for example, as a result of malware activity. After the security system is activated, a banner is displayed in the browser warning the user about a potential threat.
In Q2 of 2016, the share of the ‘Global Internet portals’ category (20.85%), which topped the rating in the first quarter, decreased considerably – by 7.84 p.p. The share of the ‘Financial organizations’ category grew 2.07 p.p. and accounted for 46.23%. This category covers ‘Banks’ (25.43%, +1.51 p.p.), ‘Payment systems’ (11.24%, -0.42 p.p.) and ‘Online stores’ (9.39%, +0.99 p.p.).
Distribution of organizations affected by phishing attacks by category, Q2 2016
The share of attacks on the ‘Social networking sites’ category increased by 2.65 p.p. and reached 12.4%. The ‘Online games’ category was also attacked more often (5.65%, + 1.96 p.p.). Meanwhile, the ‘Telephone and Internet service providers’ (4.33%) and the ‘IMS’ (1.28%) categories lost 1.17 p.p. and 2.15 p.p. respectively.Hot topics this quarter The Olympics in Brazil
For a number of years now Brazil has been among the countries with the highest proportion of users targeted by phishing. In 2015 and 2016 phishers have focused on the Rio Olympic Games in Brazil. Last quarter showed that as well as ordinary users, the potential victims of phishing included the organizers of the Olympic Games.
The Olympic theme remained popular in Q2, with phishers working overtime to send out fake notifications about big cash wins in a lottery that was supposedly organized by the Brazilian government and the Olympic Committee.‘Porn virus’ for Facebook users
Facebook users are often subjected to phishing attacks. During one attack in the second quarter, a provocative video was used as bait. To view it, the user was directed to a fake page imitating the popular YouTube video portal, and told to install a browser extension.
This extension requested rights to read all the data in the browser, potentially giving the cybercriminals access to passwords, logins, credit card details and other confidential user information. The extension also distributed more links on Facebook that directed to itself, but which were sent using the victim’s name.Phisher tricks Compromising domains with good reputation
To bypass security software filters, fraudsters try to place phishing pages on domains with good reputations. This significantly reduces the probability of them being blocked and means potential victims are more trusting. The phishers can strike it big if they can use a bank or a government agency domain for their purposes. In Q2, we came across a phishing attack targeting the visitors of a popular Brazilian e-commerce site: the fake page was located on the domain of a major Indian bank. This is not the first time fraudsters have compromised the domain of a large bank and placed their content on it.
Phishing pages targeting the users of the Brazilian store americanas.com
When trying to purchase goods on the fake pages of the store, the victim is asked to enter lots of personal information. When it’s time to pay, the victim is prompted to print out a receipt that now shows the logo of a Brazilian bank.
The domains of state structures are hacked much more frequently by phishers. In Q2 2016, we registered numerous cases where phishing pages were located on the domains belonging to the governments of various countries. Here are just a few of them:
Phishing pages located on the domains of government authorities
The probability of these links being placed on blacklists is negligible thanks to the reputation of the domain.TOP 3 organizations attacked
Fraudsters continue to focus most of their attention on the most popular brands, enhancing their chances of a successful phishing attack. More than half of all detections of Kaspersky Lab’s heuristic anti-phishing component fall on phishing pages hiding behind the names of fewer than 15 companies.
The TOP 3 organizations attacked most frequently by phishers accounted for 23% of all phishing links detected in Q2 2016.Organization % of detected phishing links 1 Microsoft 8.1 2 Facebook 8.03 3 Yahoo! 6.87
In Q2 2016, this TOP 3 ranking saw a few changes. Microsoft was the new leader with 8.1% (+0.61 p.p.), while Facebook (8.03%, +2.32 p.p.) came second. The share of attacks targeting Yahoo! (6.87%) fell 1.46 p.p., leaving last quarter’s leader in third.
Q2 leader Microsoft is included in the ‘Global Internet portals’ category because the user can access a variety of the company’s services from a single account. This is what attracts the fraudsters: in the event of a successful attack, they gain access to a number of services used by the victim.
Example of phishing on Live.com, a Microsoft serviceConclusion
In the second quarter of 2016, the proportion of spam in email traffic increased insignificantly – by 0.33 p.p. – compared to the previous quarter and accounted for 57.25%. The US remained the biggest source of spam. As in the previous quarter, the top three sources also included Vietnam and India.
Germany was once again the country targeted most by malicious mailshots, followed closely by China. Japan, which was seventh in the previous quarter’s ranking, completed the TOP 3 in Q2.
Trojan-Downloader.JS.Agent remained the most popular malware family distributed via email. Next came Trojan-Downloader.VBS.Agent and Trojan-Downloader.MSWord.Agent. A significant amount of malicious spam was used to spread ransomware Trojans such as Locky. For almost a month, however, cybercriminals did not distribute their malicious spam, but then the Necurs botnet began working again. We don’t expect to see any significant reduction in the volume of malicious spam in the near future, although there may be changes in email patterns, the complexity of the malware, as well as the social engineering methods used by attackers to encourage a user to launch a malicious attachment.
The focus of phishing attacks shifted slightly from the ‘Global Internet portals’ to the ‘Financial organizations’ category.
The theme of the Olympic Games was exploited by both phishers and spammers to make users visit fake pages with the aim of acquiring their confidential information or simply to get their money.
Events in the political arena, such as the presidential election in the US, also attracted spammers, while the sites of government agencies were compromised in phishing attacks.
As we can see, the overriding trend of the quarter is that of fraud and making quick money from victims using direct methods such as Trojan cryptors that force unprotected users to pay a ransom, or phishing attacks that target financial organizations, rather than long drawn-out scams. All of this once again highlights the need for both comprehensive protection on computers and increased vigilance by Internet users.
Kaspersky Lab has observed new waves of attacks that started on the 8th and the 27th of June 2016. These have been highly active in the Middle East region and unveiled ongoing targeted attacks in multiple regions. The attackers try to lure targets through spear phishing emails that include compressed executables. The malware collects all data such as passwords, keystrokes and screenshots, then sends it to the attackers.
#OpGhoul targeting industrial, manufacturing and engineering organizations in 30+ countriesTweet
We found that the group behind this campaign targeted mainly industrial, engineering and manufacturing organizations in more than 30 countries. In total, over 130 organizations have been identified as victims of this campaign. Using the Kaspersky Security Network (KSN) and artifacts from malware files and attack sites, we were able to trace the attacks back to March 2015. Noteworthy is that since the beginning of their activities, the attackers’ motivations are apparently financial, whether through the victims’ banking accounts or through selling their intellectual property to interested parties, most infiltrated victim organizations are considered SMBs (Small to Medium size businesses, 30-300 employees), the utilization of commercial off-the-shelf malware makes the attribution of the attacks more difficult.
In total, over 130 organizations have been identified as victims of Operation Ghoul #OpGhoulTweet
In ancient Folklore, the Ghoul is an evil spirit associated with consuming human flesh and hunting kids, originally a Mesopotamian demon. Today, the term is sometimes used to describe a greedy or materialistic individual.Main infection vector: malicious emails
The following picture represents emails that are being used to deliver malware to the victims, in what looks like a payment document. The e-mails sent by attackers appear to be coming from a bank in the UAE, the Emirates NBD, and include a 7z file with malware. In other cases, victims received phishing links. A quick analysis of the email headers reveals fake sources being utilised to deliver the emails to victims.
In the case of spear phishing emails with an attachment, the 7z does not contain payment instructions but a malware executable (EmiratesNBD_ADVICE.exe). We have observed executables with the following MD5s:
Malware MD5 hashes
Email file MD5 hashes
The spear phishing emails are mostly sent to senior members and executives of targeted organizations, most likely because the attackers hope to get access to core intelligence, controlling accounts and other interesting information from people who have the following positions or similar:
- Chief Executive Officer
- Chief Operations Officer
- General Manager
- General Manager, Sales and Marketing
- Deputy General Manager
- Finance and Admin Manager
- Business Development Manager
- Export manager
- Finance Manager
- Purchase manager
- Head of Logistics
- Sales Executive
The malware is based on the Hawkeye commercial spyware, which provides a variety of tools for the attackers, in addition to malware anonymity from attribution. It initiates by self-deploying and configuring persistence, while using anti-debugging and timeout techniques, then starts collecting interesting data from the victim’s device, including:
- Clipboard data
- FileZilla ftp server credentials
- Account data from local browsers
- Account data from local messaging clients (Paltalk, Google talk, AIM…)
- Account data from local email clients (Outlook, Windows Live mail…)
- License information of some installed applications
#OpGhoul malware collects all data such as #passwords, keystrokes and screenshotsTweet
Data is collected by the attackers using primarily:
Http GET posts
- Sent to hxxp://126.96.36.199
- mail.ozlercelikkapi[.]com (188.8.131.52), mail to info@ozlercelikkapi[.]com
- mail.eminenture[.]com (184.108.40.206), mail to eminfo@eminenture[.]com
Both ozlercelikkapi[.]com and eminenture[.]com seem to belong to compromised organisations operating in manufacturing and technology services.Malware command center
The malware connects to 220.127.116.11 to deliver collected information from the victim’s PC. This information includes passwords, clipboard data, screenshots…
The IP address 18.104.22.168 seems to belong to a compromised device running multiple malware campaigns.Victim information
Victim organizations are distributed in different countries worldwide with attackers focused on certain countries more than others:
Number of Victim Organisations by Country
Countries marked as “others” have less than three victim organizations each, they are: Switzerland, Gibraltar, USA, Sweden, China, France, Azerbaijan, Iraq, Turkey, Romania, Iran, Iraq and Italy.Victim industry information
Victim industry types were also indicators of targeted attacks as attackers were looking to infiltrate organizations that belong to the product life cycle of multiple goods, especially industrial equipment.
#Manufacturing #transportation #travel targets of #OpGhoulTweet
Number of Victim Organizations by Industry Type
Victim industry descriptionIndustrial Petrochemical, naval, military, aerospace, heavy machinery, solar energy, steel, pumps, plastics Engineering Construction, architecture, automation, chemical, transport, water Shipping International freight shipping Pharmaceutical Production/research of pharmaceutical and beauty products Manufacturing Furniture, decor, textiles Trading Industrial, electronics and food trading Education Training centers, universities, academic publishing Tourism Travel agencies Technology/IT Providers of IT technologies and consulting services Unknown Unidentified victims The last attack waves
Kaspersky Lab user statistics indicate the new waves of attacks that started in June 2016 are focused on certain countries more than others.
#opghoul highly active in #MiddleEastTweet
Hundreds of detections have been reported by Kaspersky Lab users; 70% of the attacked users were found in the United Arab Emirates alone, the other 30% were distributed in Russia, Malaysia, India, Jordan, Lebanon, Turkey, Algeria, Germany, Iran, Egypt, Japan, Switzerland, Bahrain and Tunisia.
Phishing pages have also been spotted through 22.214.171.124, and although they are taken down quickly, more than 150 user accounts were identified as victims of the phishing links sent by the attackers. Victims were connecting from the following devices and inserting their credentials, a reminder that phishing attacks do work on all platforms:
- Mac OS X
The malware files are detected using the following heuristic signatures:
Operation Ghoul is one of the many attacks in the wild targeting industrial, manufacturing and engineering organizations, Kaspersky Lab recommends users to be extra cautious while checking and opening emails and attachments. In addition, privileged users need to be well trained and ready to deal with cyber threats; failure in this is, in most cases, the cause behind private or corporate data leakage, reputation and financial loss.Indicators of Compromise
The following are common among the different malware infections; the presence of these is an indication of a possible infection.Filenames and paths related to malware
Malware links observed on 126.96.36.199 dating back to March and April 2016:
For more information on how you can protect your business from similar attacks, please visit this post from Kaspersky Business.
August 13, 2016 saw the beginning of a truly bizarre episode. A new identity going under the name ‘ShadowBrokers’ came onto the scene claiming to possess files belonging to the apex predator of the APT world, the Equation Group [PDF]. In their initial leak, the ShadowBrokers claimed the archive was related to the Equation group, however, they didn’t provide any technical details on the connections.
Along with some non-native rants against ‘Wealthy Elites’, the ShadowBrokers provided links to two PGP-encrypted archives. The first was provided for free as a presumptive show of good faith, the second remains encrypted at the time of writing. The passphrase is being ‘auctioned’, but having set the price at 1 million BTC (or 1/15th of the total amount of bitcoin in circulation), we consider this to be optimistic at best, if not ridiculous at face value.
The first archive contains close to 300MBs of firewall exploits, tools, and scripts under cryptonyms like BANANAUSURPER, BLATSTING, and BUZZDIRECTION. Most files are at least three years old, with change entries pointing to August 2013 the newest timestamp dating to October 2013.
As researchers continue to feast on the release, some have already begun to test the functional capabilities of the exploits with good results.
Having originally uncovered the Equation group in February 2015, we’ve taken a look at the newly released files to check for any connections with the known toolsets used by Equation, such as EQUATIONDRUG, DOUBLEFANTASY, GRAYFISH and FANNY.
While we cannot surmise the attacker’s identity or motivation nor where or how this pilfered trove came to be, we can state that several hundred tools from the leak share a strong connection with our previous findings from the Equation group.The Devil’s in the Crypto
The Equation group uses the RC5 and RC6 encryption algorithms quite extensively throughout their creations. RC5 and RC6 are two encryption algorithms designed by Ronald Rivest in 1994 and 1998. They are very similar to each other, with RC6 introducing an additional multiplication in the cypher to make it more resistant. Both cyphers use the same key setup mechanism and the same magical constants named P and Q.
The particular RC5/6 implementation from Equation group’s malware is interesting and deserves special attention because of its specifics. Inside the Equation group malware, the encryption library uses a subtract operation with the constant 0x61C88647. In most publicly available RC5/6 code, this constant is usually stored as 0x9E3779B9, which is basically -0x61C88647. Since an addition is faster on certain hardware than a subtraction, it makes sense to store the constant in its negative form and adding it instead of subtracting. In total, we’ve identified 20 different compiled versions of the RC5/6 code in the Equation group malware.
Encryption-related code in a DoubleFantasy (actxprxy32.dll) sample
In the screenshot above, one can observe the main loop of a RC6 key setup subroutine extracted from one of the Equation group samples. The ShadowBrokers’ free trove includes 347 different instances of RC5/RC6 implementations. As shown in the screenshot below, the implementation is functionally identical including the subtraction of the inverted constant 0x61C88647.
Specific RC6 implementation from “BUSURPER-2211-611.exe” (md5: 8f137a9100a9fcc8b512b3729878a373
Comparing the older, known Equation RC6 code and the code used in most of the binaries from the new leak we observe that they are functionally identical and share rare specific traits in their implementation.
In case you’re wondering, this specific RC6 implementation has only been seen before with Equation group malware. There are more than 300 files in the Shadowbrokers’ archive which implement this specific variation of RC6 in 24 different forms. The chances of all these being faked or engineered is highly unlikely.
This code similarity makes us believe with a high degree of confidence that the tools from the ShadowBrokers leak are related to the malware from the Equation group. While the ShadowBrokers claimed the data was related to the Equation group, they did not provide any technical evidence of these claims. The highly specific crypto implementation above confirms these allegations.
More details about the ShadowBrokers leak and similarities with Equation group are available to Kaspersky Intelligence Services reports’ subscribers. For more information, email email@example.com