New Zeus variant stymies malware analysis, has rootkit capabilities

As expected, variants of the infamous Zeus banking Trojan are becoming more adept at hiding their presence from users and AV solutions, and at preventing malware analysis tools from examining them.

As reported in December, some Zeus variants now come equipped with a 64-bit version of the malware embedded in them, to be served to targets preferring a 64-bit browser. They also have a Tor component that runs a Tor client as a hidden service and reports to the C&C server and, acting also as a server, allows bot masters to access the victims’ computer and execute malicious code.

But the biggest news is the improvement of evasion techniques.

Trend Micro researchers have discovered a new variant that is, along with all of this, also able to prevent the execution of popular analysis tools such as OllyDbg, WinHex, StudPE, ProcDump and others.

It also has rootkit capabilities, and is able to hide files and folders it drops (Windows’ File Explorer doesn’t show them), processes it starts, and registry keys it creates. According to the researchers, some of these files and folders can be detected and deleted in Windows Safe Mode.

“This 64-bit version for ZeuS/ZBOT is an expected progression for the malware, especially after ZeuS source code was leaked back in 2011,” the researchers noted.

“Since then, we have seen several reincarnations of the malware, most notably in the form of KINS and its involvement with other malware such as Cryptolocker and UPATRE. Adding other functionalities such as rootkit capability and the use of a Tor component are further proof that we can see more modifications in the future, particularly those that help circumvent or delay antimalware efforts.”