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'Malvertising' is a relatively new term for a technique used to distribute malware via advertising networks, which have long since become a popular medium among cybercriminals. In the past four years, hundreds of millions of users have fallen victim to 'viral' advertising, including visitors to major media sites, such as NY Times, London Stock Exchange, Spotify, USNews, TheOnion, Yahoo!, and YouTube. The complicated situation with ad networks even prompted the United States Senate Permanent Subcommittee on Investigations to conduct an in-depth inquiry, which produced recommendations on stepping up security and increasing the responsibilities of advertising platform owners.
At the turn of the year 2.5 million Yahoo users were attacked. Soon after the incident, a company called Fox IT published a detailed analysis of the attack. Curiously, according to Fox IT, not all Yahoo! users were affected by the attack – only residents of European countries, primarily Romania, the UK and France. Fox IT analysts believe that the attackers probably used targeted advertising mechanisms, i.e., they paid for 'impressions' served to a certain audience from the countries mentioned above. Here is an illustration of how attacks are conducted via ad networks: an overall attack organization diagram (on the left-hand side) and a specific example of the attack against Yahoo! users (on the right-hand side).
In the past, we have written about targeted attacks conducted via trusted websites (so-called watering-hole attacks) and social engineering on social networks and in IM clients. Specifically, we wrote that a cybercriminal has to do two things in order to implement a watering-hole attack: first, compromise a trusted website and second, surreptitiously inject malicious scripts into the site's code. Successful attacks via social networks or IM clients also make certain demands of cybercriminals – at the very least, to win the users' trust and increase the chances of them clicking on links sent by the attackers.
What sets attacks via ad networks apart is that in these attacks the cybercriminals do not have to compromise websites or gain the trust of potential victims. All they have to do is find an ad provider from which to buy 'impressions' or become a provider themselves (like BadNews). The remaining work, related to distributing malicious code, will be done by the ad network –the trusted site itself will download malicious scripts to its page via iframe.
Moreover, users don't even have to click on the ads – as part of its attempt to display a banner on the web page, the browser executes the banner's SWF/JS code, which automatically redirects the user to a site hosting the landing page of a popular exploit pack, such as Blackhole. A drive-by attack will follow: the exploit pack will attempt to choose an appropriate exploit to attack a vulnerability in the browser or its plugins.
The problem of ad networks being used to distribute malware and conduct targeted attacks (taking advantage of their targeted advertising capabilities) does not only affect those who use browsers to access websites. It also applies to users of applications that can display adverts, such as IM clients (including Skype), email clients (Yahoo! included), etc. And, most importantly, the problem affects the huge number of mobile app users, since these apps also connect to ad networks!
Essentially, mobile applications are different in that the SDKs commonly used for embedding adverts into apps (such as AdMob, Adwhirl etc.) do not support the execution of arbitrary code supplied by ad providers, as is the case with website advertising. In other words, only static data is accepted from the server supplying ads, including images, links, settings etc. However, cybercriminals can also create SDKs, just like media companies. The former offer developers higher per-click rates than their legitimate competitors. This is why developers of legitimate mobile software embed malicious 'advertising' code – essentially backdoors – into their apps. Moreover, legitimate SDKs may have vulnerabilities enabling the execution of arbitrary code. Two such cases were identified late last year – one involving the HomeBase SDK, the other involving AppLovin SDK.
The question "How should a corporate network be protected against attacks conducted via ad networks?" does not have a simple answer, particularly if you keep in mind possible targeted attacks. As we mentioned before, protection needs to cover not only workstations (browsers, IM clients, email clients and other applications that have dynamic advertising built into them), but also mobile devices that can access the corporate network.
Clearly, protecting workstations requires at least a Security Suite class anti-malware solution, which must include:
- protection against vulnerability exploitation;
- advanced HIPS with access restriction features, as well as heuristic and behavioral analysis (including traffic analysis);
- tools for monitoring the operating system (System Watcher or Hypervisor) in case the system does get infected.
For more reliable protection of workstations, it is prudent to use application control technology, collect statistics (inventory) on the software used on the network, set up updating mechanisms and enable Default Deny mode.
Unfortunately, compared to the protection of workstations, mobile device protection is still in the early stages of evolution. It is extremely difficult to implement a full-scale Security Suite or Application Control solution for mobile devices, since that would require modifying firmware, which is not always possible. This is why Mobile Device Management (MDM) technology is currently the only effective tool for protecting mobile devices that connect to the corporate network. The technology can control which applications are allowed to be installed on a device and which are not.
Cybercriminals have used ad networks to distribute malware for years. At the same time, the advertising market is rapidly growing, branching out into new platforms (large websites, popular applications, mobile devices), attracting new advertisers, partners, intermediaries and aggregators, which are intertwined into an extremely tangled network. The ad network problem is one more example showing that rapid technology development is not always accompanied by the corresponding evolution of security technologies.
The biggest security news of the week is the leaked photos of many celebrities. Many people, especially the involved celebrities, wondered how such a hack could take place.
The initial statement by the attacker was that the iCloud was hacked. This prompted Apple into their we-do-not-really-comment-until-we-have-done-our-research mode. Today, they released a statement on the incident:
For me the most interesting quote is: “accounts were compromised by a very targeted attack on user names, passwords and security questions, a practice that has become all too common on the Internet.”
Apple is thus well aware of the problems that arise with these forms of authentication. The more interesting is their advice: strong passwords and two-step-verification.
Strong passwords are, according to Apple, passwords with a minimum of 8 characters, with some additional requirements. Interesting enough they do not enforce of all their suggestions. A password such as “Password1″ is acceptable, even though it can be easily guessed.
Their other advice, using two-factor-authentication is somewhat flawed. For instance, it does not protect your iCloud backups (see this post). Also, two-step-verification is not available in every country. If you use, for example, a Romanian or a Croatian telephone number, then bad luck. Considering that Google offers two factor authentication for such countries as well, one might wonder why Apple didn’t implement it as well. Could it be the cost of the SMSes?
So how to protect yourself properly? My colleague Alex Savitsky wrote an excellent article about this.
- Use strong and unique passwords that are easy to remember and hard to crack (for instance, a phrase in your native language with “spaces” in it, a number and a special char)
- If available in your country, enable two-factor authentication
- iPhone users may want to disable iCloud photo Stream / photo Sharing. Additionally iPhone users may want to delete the backup of their photos / iPhone in the iCloud.
Photo courtesy of my colleague Dmitry Bestuzhev – https://twitter.com/dimitribest/status/506820178320322560
And remember – if you don’t want your private photos to get leaked, better not take them in the first place!
We spotted an interesting attack from Brazilian bad guys aiming to change the DNS settings of home routers by using a web-based attack, some social engineering, and malicious websites. In these attacks the malicious DNS servers configured in the user's network device are pointed towards phishing pages of Brazilian Banks, programmed to steal financial credentials.
Attacks targeting home routers aren't new at all; in 2011, my colleague Marta described malware targeting network devices like these. In Brazil we documented a long and painful series of remote attacks that started in 2011-2012 that affected more than 4.5 million DSL modems, exploiting a remote vulnerability and changing DNS configurations. But this "web-based" approach was something new to Brazilian bad guys until now and we believe it will spread quickly amongst them as the number of victims increases.
The attack starts with a malicious e-mail and a bit of social engineering, inviting you to click:
"I'm your friend and want to tell you you're being cheated, look at the pics"
How many people believe in it? Well, many: 3.300 clicks in 3 days, with most of the users located in Brazil, US and China, probably Brazilians living there or people that understand Portuguese:
Shortened URLs are a cheap way for the bad guy measure their 'performance'
The website linked in the message is full of adult content, porn pics. While in the background it starts running scripts. Depending on your configuration, at some point the website may ask for the username and password of your wireless access point – if it has, this is a good thing. If not, this may be a problem for you:
The script located in the website will try to guess the password of your home router. It tries several combinations such as "admin:admin":
or "admin:gvt12345" (GVT is a big Brazilian ISP):
The scripts will continue trying combinations that point to the control panel of your network device such as [your-router-IP].rebootinfo.cgi or [your-router-IP].dnscfg.cgi?. Each script includes the commands to change the primary and secondary DNS servers. If you're using default credentials in your home router, there won't be an interaction and you'll never realize that the attack has occurred. If you're not using default credentials, then the website will pop up a prompt asking you to enter it manually.
We found Brazilian bad guys actively using 5 domains and 9 DNS servers – all of them hosting phishing pages for the biggest Brazilian Banks. The malicious websites used in the attacks are filtering direct access by using HTTP referrers, thus aiming to prevent direct access from security analysts.
So how do you protect yourself? Make sure you're not using the default password in your home router and NEVER enter your credentials into any website asking for them. Our Kaspersky Internet Security is also prepared to block such scripts automatically.
Anyone using the Internet is at risk, regardless of age and regardless of what they like to do online. Cybercriminals can deploy an impressive arsenal, targeting everyone from schoolchildren to pensioners and following them whether they are logged on to social networks, checking the latest headlines or watching their favorite videos. Internet scammers want access to our money, our personal data and the resources of our computer systems. In short, they want anything that they can profit from.
There are a huge range of different attacks facing us on the net: users can get caught by ransomware like Gimeno or Foreign, become part of the Andromeda botnet, see ZeuS/Zbot drain the cash from their bank accounts, or have their passwords compromised by Fareit spyware. Usually web attacks try to download and install an infected executable file on the target computer, but there are some exceptions, for instance XSS or CSRF, which execute embedded HTML code.Attack mechanism
For an attack to succeed, first of all users need to connect to a malicious site that downloads an executable file onto their computers. To tempt users to the resource, scammers might send them a link by email, SMS or via a social network. They might also try to promote their site via search engines. One further technique is to hack a popular legitimate resource and turn it into an instrument to attack its visitors.
Downloading and installing malware can be done in one of two ways. The first, a hidden drive-by download, relies on using a vulnerability in the user's software. The user of the infected site is often completely unaware that the computer is installing the malware, as usually there are no indications that this is happening.
The second method uses social engineering, where users are tricked into downloading and installing malware themselves, believing it is an updated flash player or some similar popular software.
Diagram of Internet attacks showing how executable malware files can be downloadedMalicious links and banners
The simplest way to lure victims to malicious sites is simply to display an attractive banner with a link. As a rule sites with illegal content, pornography, unlicensed software, films etc. are used as a host. Such sites can work "honestly" for a long time to build up an audience before they start hosting banners with links to malicious resources.
One popular infection method is malvertising, or the redirecting the user to a malicious site with the help of hidden banners. Dubious banner networks attract site administrators with high payments for 'click-throughs' on their ads and frequently earn money "on-the-side" by spreading malware.
When users enter the site displaying these banners, a so-called "pop-under" opens in the victim's browser. This is similar to a pop-up window, but it appears either under the main window of the site, or on an otherwise inactive neighboring tab. The contents of these "pop-unders" often depend on the location of the visitor to the site - the inhabitants of different countries are redirected to different resources. The visitors of one country might simply be shown an advert for example
Site sends American visitors to the resource watchmygfnet
Site sends Russian visitors to the resource runetkitv\
…whereas visitors from other countries will be attacked by exploit packs.
An inhabitant of Japan is attacked by an exploit and infected with the Zbot spyware Trojan
On occasion these malicious banners can even penetrate into honest banner networks, despite careful scrutiny by administrators. Cases like this have affected the Yahoo Advertising banner network and even YouTube.Spam
Spam is one of the most popular means of attracting victims to malicious resources. It includes messages sent by email, SMS and instant communications systems, via social networks, private messages on forums and comments in blogs.
A dangerous message might contain a malicious file or a link to an infected site. To encourage the user to click on a link or a file social engineering is used, for example:
- the name of a real organization or person is used as the sender's name,
- the letter pretends to be part of a legitimate mailshot or even a personal communication,
- the file is presented as a useful program or document.
During targeted attacks, when cybercriminals specifically attack a certain organization, the malicious letter might mimic a letter from a regular correspondent: the return address, content and signature could be the same as a genuine letter, for example from a partner of the company. By opening the attached document with a name like "invoice.docx" users put their computers at risk of infection.Black Search Engine Optimization
SEO or Search Engine Optimization is a collection of techniques to raise the position of a site in the results given by search engines. Modern users often go to search engines to find necessary information or services, so the easier it is to find a given site the more visitors it will get.
In addition to legitimate methods of optimization, those that are permissible in the eyes of the search engines, there are forbidden techniques that fool search engines. A site might "promote itself" with the help of a botnet - thousands of bots make certain search requests and select the malicious site, raising its rating. The site itself may adopt a different appearance depending on who has entered it: if it is a search robot it will be shown a page relevant to the request, if it is a normal user it will be redirected to a malicious site.
Also links to the site are distributed in forums and other sites known to search engines using special utilities, which raise the rating of the site and, consequently, its position in search results.
As a rule, sites that use black search optimization are actively blocked by search engine administrators. For this reason they are created by the hundred using automatic instruments.Infected legitimate sites
Sometimes cybercriminals infect popular legitimate sites in order to spread their programs. These might be high-traffic news resources, internet shops or portals and news aggregators.
There are two common ways to infect sites. If a software vulnerability was detected on the target site, malicious code can be inserted (for instance an SQL injection). In other cases the malefactors obtain authentication data from the site administrator's computer using one of the many Trojan spyware programs or using phishing and social engineering and seize control of the site. Once under the control of the criminals, the site can be infected in one way or another. The simplest approach is to use a hidden iframe tag with a link to the malicious resource added to the HTML code of the page.
Kaspersky Lab registers thousands of legitimate sites every day that download malicious code to their visitors with them being aware of it. Among the most prominent cases were the Lurk Trojan found on the site of the RIA Novosti news agency and gazeta.ru and the infection of PHP.Net
Visitors to an infected site are attacked with the use of hidden drive-by-downloads. The infection goes unnoticed by the users and does not require them to download or activate anything. An exploit, or set of exploits, is automatically downloaded from the page and, if the targeted machine has vulnerable software, a malicious executable is launched.Exploit packs
The most effective tool to infect a victim's computer is an exploit pack, such as Blackhole. These are hot products on the black market: exploit packs are developed to order or for widespread sale and are supported and updated. The price depends on the quantity and "freshness" of the exploits included, the ease of administration, the quality of the support, the regularity of updates and the greed of the seller.
As these attacks take place through the browser, the exploits have to use a vulnerability in either the browser itself, add-ons to it or third party software loaded by the browser to handle content. If one of these exploits is used successfully, a malicious file will be launched on the victim's machine.
Typical set of add-ons for the Internet Explorer browser that have permission to run by default. Add-ons the vulnerabilities in which are often used to attack a system are underlined in red.
An effective pack will contain exploits for useful vulnerabilities in popular browsers and their add-ons, and also for Adobe Flash Player and other popular programs. Often exploit packs have tools for fine tuning and collecting infection statistics.
Styx exploit pack control panelDirect download by users
Quite often cybercriminals don't need ingenious and expensive tools to insert their malicious programs onto users' computers. Users can simply be fooled into downloading and running malware themselves.
For instance, on entering a malicious site a user sees a preview video "for adults only". Clicking on this brings up a message to update Adobe Flash Player, and at the same time the site immediately offers him a file to download with an authentic sounding name. By installing the "update" the user infects the computer with a Trojan.
Message appearing when trying to view an "adult" video on a malicious site
Or a web-page might appear imitating the "My Computer" window, saying that a large number of viruses have been detected on the computer. And nearby a window opens offering a free "antivirus" program to cure the problems.
An apparent offer to install a free antivirus program hiding a TrojanInfection via social networks
Instructions for the installation of a semi-automatic Facebook worm
After these actions are carried out the worm activates and begins collecting data on the user, sending links to itself to the victim's contacts, awarding "likes" to various posts. This last option is a paid service that the owner of the worm offers to customers. And so we come to the reason why cybercriminals go to all this trouble and break the law.Money, money, money
Naturally nobody is attacking our computers for the intellectual challenge — the aim is money. One very popular way of illegally making money from victims is the use of Trojan ransom-ware, making it impossible to use the computer until a certain sum has been paid.
Having penetrated the user's computer the Trojan determines the country where the infected computer is and shows the victim the corresponding disable screen, containing threats and instructions on how to pay the ransom. The language of the message and the payment method suggested by the cybercriminals both depend on the user's country.
Usually the evildoers accuse the user of looking at child pornography or some other illegal action and then threaten a criminal investigation or to make the matter public. The assumption is that the victim will take these threats seriously and won't risk seeking help from law enforcement agencies. In some cases the Trojan ransom-ware may threaten to destroy the contents of the hard disk if the ransom is not paid quickly.
The disable screen that Trojan-Ransom.Win32.Foreign shows users in the USA
The cybercriminals offer the option of paying this "fine" by sending an SMS to a premium number or making a money transfer using one of the payment systems. In return the user should receive an unblocking key to deactivate the Trojan, but in practice this doesn't always happen.
Maintaining a communication channel with the victim can lead law enforcement agencies to the criminals and they frequently prefer not to take the risk, leaving the victim with a practically useless computer.
Another common method of illegal moneymaking is the collection and sale of users' confidential data. Contact details and personal data are tradable commodities that can be sold on the black market, albeit not for a great deal of money. However, it can be a profitable sideline, especially as the collection of information does not necessarily require any malware infection. Often the victims themselves supply all the necessary information — the important thing is for the site hosting the form for the entry of data to appear reliable and authentic.
A false site collecting contact details and personal information of visitors and then signing them up for paid mobile services
Banking Trojans bring their operators large profits. These programs are designed to steal money from users' bank accounts using distance banking systems. Malware of this type steals users' authentication data for online banking systems. Usually this is not enough as almost all banks and payment systems require authentication using several factors - entering an SMS code, inserting a USB key etc. In these cases the Trojan waits until the user makes a payment using internet banking and then changes the payment details, diverting the money to special accounts from which the criminal can cash out. There are other ways around two factor authentication: the Trojan might intercept messages with single use passwords or freeze the system at the moment the USB key is inserted, leaving the user powerless while the criminals hijack the operation and steal the money.
Finally, another profitable business is running botnets. The infected computers in a botnet can, unnoticed, be used by the evildoers for various money-making activities: mining bitcoins, sending spam, carrying out DDOS attacks, and boosting sites' ratings through search requests.Counteracting threats
As we have already shown, internet threats are diverse and can threaten users almost anywhere — when reading their mail, interacting on social networks, checking the news or simply surfing. There are also many ways to protect against these threats, but they can be summarized in four keys pieces of advice:
- Always pay attention to what you are doing on the Internet: which sites you visit, which files you download and what you run on your computer.
- Do not trust messages from unknown users and organizations, do not click on links and do not open attachments.
- Regularly update frequently-used software, especially software that works with your browser
- Install up-to-date defenses and keep anti-virus databases current.
It all sounds very simple, but the growing number of infections clearly demonstrates that too many users fail to take their safety seriously and neglect to follow this advice. We hope that our overview of current internet threats will help improve the situation.
There is currently a lot of buzz about the Backoff point-of-sale Trojan that is designed to steal credit card information from computers that have POS terminals attached.
Although very thorough, the existing public analyses of Backoff are missing a very relevant piece of information: the command-and-control (C&C) servers. However, if you have access to the samples it isn't hard to extract this information. At the end of this document, you can find a full list together with other IOCs (indicators of compromise).
Backoff malware configuration, with C&Cs
We sinkholed two C&C servers that Backoff samples used to communicate with their masters. These C&C servers are used by certain samples that were compiled from January - March 2014. Over the past few days, we observed over 100 victims in several countries connecting to the sinkhole.Statistics:
There were several interesting victims among them:
- A global freight shipping and transport logistics company with headquarters in North America.
- A U.K.-based charitable organization that provides support, advice and information to local voluntary organizations and community groups.
- A payroll association in North America.
- A state institute connected with information technology and communication in Eastern Europe.
- A liquor store chain in the U.S.
- An ISP in Alabama, U.S.
- A U.S.-based Mexican food chain.
- A company that owns and manages office buildings in California, U.S.
- A Canadian company that owns and operates a massive chain of restaurants.
There are also a lot of home user lines, mostly in the U.S. and Canada, connecting to the sinkhole. This is to be expected as many smaller businesses generally tend to run those rather than dedicated corporate connections.Conclusions
The success of Backoff paints a very bleak picture of the state of point-of-sale security. Our sinkhole covers less than 5% of the C&C channels and the sinkholed domains only apply to certain Backoff samples that were created in the first quarter of this year. Yet, we've seen more than 85 victims connecting to our sinkhole.
Most of these victims are located in North America and some of them are high profile. Taking into account the U.S. Secret Service statement, it's a pretty safe bet that the number of Backoff infections at businesses in North America is well north of 1,000.
Since its appearance last year, Backoff has not changed dramatically. The author created both non-obfuscated and obfuscated samples. This was likely done to defeat the security controls on the targeted networks. However, the defenses running on a PoS terminal and/or network should not have been affected by this. This speaks volumes about the current state of PoS security, and other cybercriminals are sure to have taken note.
It's very clear that PoS networks are prime targets for malware attacks. This is especially true in the US, which still doesn't support EMV chip-enabled cards. Unlike magnetic strips, EMV chips on credit cards can't be easily cloned, making them more resilient. Unfortunately, the US is adopting chip and signature, rather than chip and PIN. This effectively negates some of the added security EMV can bring.
This may prove another costly mistake. Not adopting EMV along with the rest of the world is really haunting retail in the U.S. and the situation is not likely to change anytime soon.IOCs / C&Cs: Trojan file paths: