Researchers find unusual malware targeting Tibetan users in cyberespionage operation

The malware abuses the Windows Management Instrumentation (WMI) service to remain undetected, researchers from ESET said

By Lucian Constantin, IDG News Service |  Security

Security researchers from antivirus vendor ESET discovered a piece of cyberespionage malware targeting Tibetan activists that uses unusual techniques to evade detection and achieve persistency on infected systems.

The malware, which was dubbed Win32/Syndicasec.A, bypasses the UAC (User Account Control) mechanism in Windows to run arbitrary commands with elevated privileges without prompting users for confirmation.

It exploits a design flaw in the Windows UAC whitelist functionality that was documents back in 2009 by a developer named Leo Davidson. In fact, the malware uses Davidson's proof-of-concept code with almost no modifications, said Alexis Dorais-Joncas, Security Intelligence Team Lead at ESET, Thursday in a blog post.

This technique is used to execute a second malicious component that registers a piece of Javascript code in the Windows Management Instrumentation (WMI) subsystem. WMI is a default Windows service that can execute scripts written by system administrators to automate administrative tasks.

The abuse of WMI in malware is not new, but is a rare occurrence, Dorais-Joncas said. "This technique has the excellent property (from the attacker's point of view) of not requiring any malicious code to be stored as a regular file on disk. This causes standard dynamic analysis tools such as Process Monitor to fail to clearly highlight the malicious activity."

The Stuxnet cyberespionage malware, which targeted Iran's nuclear fuel enrichment plant at Natanz, also used this technique, he said.

The rogue WMI script added by the malware makes HTTP requests to hardcoded URLs that point to the RSS feeds of free blog sites. The title tags of RSS entries in those feeds contain encrypted commands that, when decoded, reveal the URLs of the actual command-and-control (C&C) servers.

When contacted, the C&C servers serve obfuscated JavaScript code that gets evaluated and executed by the WMI script running on the infected computers. This code contains the commands issued by the attackers.

The ESET researchers infected a test machine with Win32/Syndicasec in order to monitor its traffic and found that the interactions between the C&C server and the malware didn't appear to be automated.

"Every day would bring different commands sent at non-regular time intervals, making it look just as if someone was sitting behind a console and manually controlling infected hosts," Dorais-Joncas said.

The observed commands suggested that the attackers were browsing through the machine's file system and were gathering details about its network settings, attached drives and running programs.

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