TeamSpy, the data-stealing malware that was associated with a decade-long cyber-espionage operation several years ago, has resurfaced in a new attack campaign, Heimdal Security researchers warn.
The malware, designed to provide its operators with full access to the compromised machines, was used in an information gathering operation that focused mainly on ordinary people, though some victims were found to be high profile industrial, research, or diplomatic targets. The malware was abusing the legitimate TeamViewer remote access tool for its nefarious operations, researchers discovered.
The newly observed attack relies on social engineering to trick potential victims into installing TeamSpy onto their computers. The malware is being distributed via spam emails that contain a malicious ZIP attachment designed to drop an infected DLL (MSIMG32.dll) on the target machine. Two other files are also downloaded onto the computer: 324.bat and 324.exe.
The same as other TeamViewer-abusing malware, the malicious app leverages DLL hijacking to abuse the legitimate software for its nefarious operations. TeamSpy includes various components of the legitimate program, such as a TeamViewer VPN and a keylogger. Upon installation, it kills a series of Windows processes to install these components and launch them.
Simultaneously, the malware copies logs to a text file and writes all usernames and passwords it can find to it. The file is then sent to the command and control (C&C) server.
The final goal of the attack, however, is to gain complete control of the infected PC and to gather confidential information from it while keeping a low profile to avoid alerting the user. For that, the malware downloads additional components, including the TeamViewer application.
“Given how the TeamSpy infection happens, it is clear that a TeamViewer session started by the attackers will be invisible to the victim. This can lead to numerous forms of abuse against the services that the logged in user runs on his/her computer,” Heimdal Security’s Andra Zaharia notes. What’s more, the attack can circumvent two-factor authentication, she says.
The newly observed payload has a low detection rate at the moment and users are advised to carefully analyze all unwanted emails and to avoid downloading attachments from unknown senders. “Malware can disguise itself in many forms on the web, and all it takes is one click to trigger an infection,” Zaharia concludes.