The Iran-linked Chafer threat group has used a new Python-based backdoor in November 2018 attacks targeting a Turkish government entity, Palo Alto Networks reveals. 

Active since at least 2014 and mainly focused on surveillance operations and the tracking of individuals, the hacking group was observed expanding its target list and the arsenal of tools over the past couple of years. 

The recently observed attacks leveraged infrastructure previously associated with the group, namely the win10-update[.]com domain and delivered the new malicious payload from IP address 185.177.59[.]70, Palo Alto Networks’ security researchers reveal. 

Dubbed MechaFlounder, the newly observed payload appears to be the first Python-based malware used by the threat actor. Used as a secondary payload, the backdoor is supposedly used for post-exploitation activities on the compromised host. 

Delivered from the attackers’ command and control (C&C) server via an HTTP request, the payload was bundled as a portable executable using PyInstaller. The backdoor allows attackers to upload and download files and run additional commands and applications on the compromised system.

Once installed, the malware enters a loop and continuously attempts to communicate with its C&C server using HTTP. Based on received commands, the backdoor can terminate connection, download/upload files, set sleep interval between C&C beacons, change the current working directory, and attempt to run supplied data as a command on the command line.

When uploading a file from the compromised system, the Trojan uses the Browser class in the mechanize module to submit the file to an HTML form on the C&C server, the security researchers explain. It also reports back on the result of executed commands. 

Analysis of the malware also revealed the use of a parameter previously seen in VBScript downloader payloads installed by delivery documents associated with both Oilrig and Chafer, which suggests the two groups might be sharing code. 

While the researchers couldn’t establish the specifics of code sharing between the two groups, the fact that the actors are collaborating isn’t surprising. In fact, Iranian actors were observed sharing malware code before. 

“MechaFlounder was created by Chafer using a combination of actor developed code and code snippets freely available online in development communities. The MechaFlounder Trojan contains enough functionality for the Chafer actors to carry out the necessary activities needed to accomplish their goals, specifically by supporting file upload and download, as well as command execution functionality,” Palo Alto Networks concludes. 

Related: Iran-Linked Hackers Use Array of Tools to Steal Data: FireEye

Related: Iran-Linked Chafer Group Expands Toolset, Targets List