Backdoor Targeting Malaysian Government a “Mash-up” of Malware

A recently observed cyber-espionage toolkit that was used in targeted attacks against the Malaysian government in mid-2018 is made up of publicly available tools and leaked source code of backdoors, ESET says. 

The ‘mash-up’ toolkit was observed in June 2018, and it immediately piqued ESET security researchers’ interest due to the use of code from well-known malicious tools, including the Gh0st RAT and NetBot Attacker. 

As ESET’s Tomáš Gardoň and Filip Kafka explain, both of these malware families were developed in 2008 and have been previously used in high-profile attacks, with the source code of both leaked online. 

In addition to code pertaining to these backdoors, the newly discovered toolkit contained parts of Hacking Team’s infamous Remote Control System (RCS) surveillance tool. This malware also had its source code leaked, and has been used to build other malicious tools. 

While such code reuse is rather common when it comes to less skilled attackers and more banal attacks, highly targeted espionage attacks against a governmental targets almost always involve custom-made malicious tools, the researchers point out. 

“We could say that these attackers wanted to achieve a lot but were willing to do only very little. Even some of the customizations they added to the reused tools – probably in an attempt to fly under the radar – were “borrowed” from Hacking Team’s code,” Gardoň notes. 

Only one of the malware’s components, a standalone file stealer, wasn’t matched to known tools. 

The toolkit, the researchers explain, works as a backdoor, allowing the attackers to exfiltrate files from compromised machines, as well as to upload files. The malware also supports modification and deletion of files, can monitor and simulate mouse and keyboard activity, gather information on the infected system, execute or kill processes, and even shut down or restart an infected computer.

Although the malware was detected and blocked, the attackers did manage to infiltrate some systems, and ESET observed the attack attempts coming from computers in the target’s network. 

The researchers believe the attackers were able to compromise a computer or server in the network, and then use this compromise to spread through the network. 

The security researchers also noticed that the attackers made several changes to the evasion techniques employed by their malware, suggesting that the attack “wasn’t just a random incident, but organized espionage against the Malaysian government.”

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