Poisoned Google Search Results Lead to Banking Trojan

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A recently observed Zeus Panda banking Trojan attack used poisoned Google search results for specific banking related keywords to infect users, Cisco Talos researchers warn.

As part of this attack, the actor behind Zeus Panda used Search Engine Optimization (SEO) to make their malicious links more prevalent in the search results. By targeting financial-related keyword searches, the actor attempted to increase the efficiency of the attack through ensuring that the infected users are regularly using financial platforms.

“By leveraging compromised web servers, the attacker was able to ensure that their malicious results would be ranked highly within search engines, thus increasing the likelihood that they would be clicked on by potential victims,” Cisco reveals.

In one specific case, the actor’s poisoned results were displayed several times on Page 1 of the Search Engine Results Page (SERP) for the targeted keyword, the researchers discovered. The attack was mainly aimed at keyword groups specific to financial institutions in India and the Middle East.

Cisco was able to identify hundreds of malicious pages that redirected victims to the malicious payload and says that the infection process included multiple stages. Moreover, the researchers observed the same redirection system and associated infrastructure being used in tech support and fake AV scams that attempted to trick victims into believing they have been infected with Zeus.

The malicious webpages use JavaScript to redirect users to an intermediary site where more JavaScript is executed, which results in an HTTP GET request to another page. Following server’s response, the victim is sent to another compromised site where a malicious Word document is hosted.

The victim is prompted to download the document, which includes malicious macros the user is lured to run. The malicious macro code is basic, but obfuscated. It was designed to download and execute a PE32 executable that results in the system being infected.

The payload is a new version of the Zeus Panda banking Trojan that can steal user’s financial credentials and other sensitive data. The payload used in this attack was multi-stage, featuring a variety of anti-analysis and evasion techniques ensuring the malware won’t execute properly in automated analysis environments, or sandboxes.

The threat first queries the system’s keyboard mapping to determine the system language and terminates itself if it detects Russian, Belarusian, Kazak, or Ukrainian keyboard layouts. It also checks if it runs in a series of sandbox environments, including VMware, VirtualPC, VirtualBox, Parallels, Sandboxie, Wine, and SoftIce. Next, it checks for tools and utilities typically used for analysis purposes.

“In an attempt to hinder analysis, the initial stage of the malicious payload features hundreds of valid API calls that are invoked with invalid parameters. It also leverages Structured Exception Handling (SEH) to patch its own code. It queries and stores the current cursor position several times to detect activity and identify if it is being executed in a sandbox or automated analysis environment,” Cisco reveals.

The malware performs a variety of other operations as well, in an attempt to make analysis significantly more difficult. For example, they create hundreds of case comparisons, thus hindering code tracing. The researchers also noticed the use of a high number of exception calls to cause sandboxes to crash, thus preventing automated analysis.

“Attackers are constantly trying to find new ways to entice users to run malware that can be used to infect the victim’s computer with various payloads. Talos uncovered an entire framework that is using ‘SERP poisoning’ to target unsuspecting users and distribute the Zeus Panda banking Trojan. In this case, the attackers are taking specific keyword searches and ensuring that their malicious results are displayed high in the results returned by search engines,” Cisco notes.

Related: Some Ideas Never Die; the Trojan is Wheeled in Again

Related:PowerShell-Abusing Banking Trojan Goes to Brazil

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Ionut Arghire is an international correspondent for SecurityWeek.

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