Pierluigi Paganini June 30, 2023

North Korea-linked cyberespionage group Andariel used a previously undocumented malware called EarlyRat.

Kaspersky researchers reported that the North Korea-linked APT group Andariel used a previously undocumented malware dubbed EarlyRat in attacks exploiting the Log4j Log4Shell vulnerability last year.

The Andariel APT (aka Stonefly) has been active since at least 2015, it was involved in several attacks attributed to the North Korean government.

The researchers speculate the threat actor is rather opportunistic and could potentially target any company around the world with good financial standing and with vulnerable Internet-exposed web services.

Kaspersky observed Andariel first infecting machines through a Log4j flaw exploitation, then the threat actors downloaded further malware from the C2 server. The experts were not able to capture the first piece of malware they downloaded from the C2, however, the researchers noticed that the exploitation was closely followed by the download of the DTrack backdoor.

The experts were able to reproduce the commands sent by the attackers, they speculate the malware was run by a human operator. 

The experts also identified a set of off-the-shelf tools used by Andariel during the command execution phase, including:

• Supremo remote desktop;
• 3Proxy;
• Powerline;
• Putty;
• Dumpert;
• NTDSDumpEx;
• ForkDump;

The malware EarlyRat was dropped via phishing messages using weaponized documents.

“EarlyRat, just like many other RATs (remote access Trojans), collects system information upon starting and sends it to the C2” reads the report published by Kaspersky.

EarlyRat is very simple, it can execute commands. The researchers found many similarities between EarlyRat and MagicRat.

“Despite being an APT group, Lazarus is known for performing typical cybercrime tasks, such as deploying ransomware, which makes the cybercrime landscape more complicated. Moreover, the group uses a wide variety of custom tools, constantly updating existing and developing new malware.” concludes the report.

“Focusing on TTPs as we did with Andariel helps to minimize attribution time and detect attacks in their early stages. This information can also help in taking proactive countermeasures to prevent incidents from happening.”

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Pierluigi Paganini

(SecurityAffairs – hacking, Andariel)