Security researchers have discovered a new Mac malware allegedly developed by APT28 Russian cyber espionage group who is believed to be responsible for 2016 presidential election hacking scandal.

A new variant of the X-Agent spyware is now targeting Apple macOS system that has previously been used in cyber attacks against Windows, iOS, Android, and Linux devices.

The malware is designed to steal web browser passwords, take screenshots of the display, detect system configurations, execute files and exfiltrate iPhone backups stored on the computer.

The X-Agent malware is tied to Russian hacking group known as APT28 — also known as Fancy Bear, Sofacy, Sednit, and Pawn Storm — that has been operating since at least 2007 and is allegedly linked to the Russian government.

"Our past analysis of samples known to be linked to APT28 group shows a number of similarities between the Sofacy/APT28/Sednit Xagent component for Windows/Linux and the Mac OS binary that currently forms the object of our investigation," Bitdefender reported in a blog post published Tuesday. 

"For once, there is the presence of similar modules, such as FileSystem, KeyLogger, and RemoteShell, as well as a similar network module called HttpChanel."

Like variants for other platforms, the Mac version of X-Agent spyware is also act as a backdoor with advanced cyber-espionage capabilities that can be customized depending on the objectives of an attack.
Moreover, X-Agent is being planted by exploiting a vulnerability in the MacKeeper software installed on the targeted computers and known malware dropper Komplex — a first-stage trojan that APT28 uses to infect machines.

Abovementioned evidence indicates that the newly discovered Mac version of X-Agent is also created by the same Russian hacking group.

Once successfully installed, the backdoor checks for the presence of a debugger and if it finds one, it terminates itself to prevent execution. But if not, the backdoor waits for an Internet connection to communicate with the command-and-control servers.

"After the communication has been established, the payload starts the modules. Our preliminary analysis shows most of the C&C URLs impersonate Apple domains," Bitdefender researchers said. 

"Once connected to the C&C, the payload sends a HelloMessage, then spawns two communication threads running in infinite loops. The former uses POST requests to send information to the C&C, while the latter monitors GET requests for commands."

The Research is still ongoing and Bitdefender security researchers right now only have the Mac malware sample and not a full picture of how an attack works.

APT28 is one of the two Russian-linked cyber-espionage groups that have been accused of hacking into the U.S. Democratic National Committee's email server last year and interfering with the 2016 presidential election.

You can read BitDefender's previous analysis on the APT28 hacking group here [PDF].