ESET researchers analyzed the cyber team's new toolsespionages Turla, which are based on PowerShell. These tools are more resistant to attacks and show improved features to avoid detection mechanisms.
The famous APT team (Advanced Persistent Threat), also known as Snake, recently started using PowerShell scripting, which can directly download and "run" malware executables and libraries.
Using PowerShell-based tools, the Turla team's cybercriminals can bypass the detection techniques that are triggered when a malicious executable appears archive on a disk.
Turla is a well-known cyber espionage team, which stands out for the use of complex malware in its attacks.
Its actions are believed to date back to at least 2008, when it was noted infringement of US military systems. It is also involved in serious attacks against many government organizations in Europe and the Middle East – including the German Foreign Ministry and the French Army.
Recently, ESET researchers have identified a number of attacks using PowerShell programming scenarios against diplomatic missions in Eastern Europe. "These are probably the same scenarios that Turla uses against other global targets," said ESET researcher Matthieu Faou, who led the study.
ESET researchers have published one article with the results of their analysis of the PowerShell scripts used by the Turla team to help deal with the attacks. "Apart from the new PowerShell loader used by Turla, we discovered and analyzed various interesting loads, such as an RPC-based backdoor and a PowerShell backdoor that uses OneDrive, Microsoft's cloud storage service, as a Command and Control server. ", Says Faou.
PowerShell loaders, which, when detected, are classified by ESET under the generic name PowerShell / Turla, stand out from the common droppers for their ability to remain in the system, as they regularly load into memory only the built-in executable files.
In some samples, the Turla cybercriminals had modified PowerShell scripts in order to bypass AMSI (Antimalware Scan Interface). This technique, which was first discovered at the Black Hat Asia 2018 conference, results in the antimalware product being unable to receive data from the AMSI for scanning.
"However, these techniques do not prevent the detection of real malicious charges in memory," explains Matthieu Faou.
Among the malicious cargoes recently used by Turla, two stand out. One is a whole set of backdoor based RPC protocols. These backdoors are used to perform sideways movement and take control of other machines on the local network without relying on an external C&C server. Also of interest is PowerStallion, a lightweight PowerShell backdoor that uses Microsoft's OneDrive cloud storage service as a Command & Control server.
"We believe this backdoor is a tool to regain access in the event that Turla's main backdoors are removed and cybercriminals can no longer access the compromised computers," said Matthieu Faou.
ESET researchers continue to closely monitor the APT Turla team and other similarly important teams, researching their methods, tactics and procedures to help organizations protect their networks.
More details can be found in the relevant article on ESET's blog, WeLiveSecurity.com.
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