North Korean Hackers Weaponize Research Lures to Deliver RokRAT Backdoor

Media organizations and high-profile experts in North Korean affairs have been at the receiving end of a new campaign orchestrated by a threat actor known as ScarCruft in December 2023.

“ScarCruft has been experimenting with new infection chains, including the use of a technical threat research report as a decoy, likely targeting consumers of threat intelligence like cybersecurity professionals,” SentinelOne researchers Aleksandar Milenkoski and Tom Hegel said in a report shared with The Hacker News.

The North Korea-linked adversary, also known by the name APT37, InkySquid, RedEyes, Ricochet Chollima, and Ruby Sleet, is assessed to be part of the Ministry of State Security (MSS), placing it apart from Lazarus Group and Kimsuky, which are elements within the Reconnaissance General Bureau (RGB).

The group is known for its targeting of governments and defectors, leveraging spear-phishing lures to deliver RokRAT and other backdoors with the ultimate goal of covert intelligence gathering in pursuit of North Korea’s strategic interests.

In August 2023, ScarCruft was linked to an attack on Russian missile engineering company NPO Mashinostroyeniya alongside Lazarus Group in what has been deemed as a “highly desirable strategic espionage mission” designed to benefit its controversial missile program.

Earlier this week, North Korean state media reported that the country had carried out a test of its “underwater nuclear weapons system” in response to drills by the U.S., South Korea, and Japan, describing the exercises as a threat to its national security.

The latest attack chain observed by SentinelOne targeted an expert in North Korean affairs by posing as a member of the North Korea Research Institute, urging the recipient to open a ZIP archive file containing presentation materials.

While seven of the nine files in the archive are benign, two of them are malicious Windows shortcut (LNK) files, mirroring a multi-stage infection sequence previously disclosed by Check Point in May 2023 to distribute the RokRAT backdoor.

There is evidence to suggest that some of the individuals who were targeted around December 13, 2023, were also previously singled out a month prior on November 16, 2023.

SentinelOne said its investigation also uncovered malware – two LNK files (“inteligence.lnk” and “news.lnk”) as well as shellcode variants delivering RokRAT – that’s said to be part of the threat actor’s planning and testing processes.

While the former shortcut file just opens the legitimate Notepad application, the shellcode executed via news.lnk paves the way for the deployment of RokRAT, although this infection procedure is yet to be observed in the wild, indicating its likely use for future campaigns.

Both LNK files have been observed deploying the same decoy document, a legitimate threat intelligence report about the Kimsuky threat group published by South Korean cybersecurity company Genians in late October 2023, in a move that implies an attempt to expand its target list.

This has raised the possibility that the adversary could be looking to gather information that could help it refine its operational playbook and also target or mimic cybersecurity professionals to infiltrate specific targets via brand impersonation techniques.

The development is a sign that the nation-state hacking crew is actively tweaking its modus operandi in an apparent effort to circumvent detection in response to public disclosure about its tactics and techniques.

“ScarCruft remains committed to acquiring strategic intelligence and possibly intends to gain insights into non-public cyber threat intelligence and defense strategies,” the researchers said.

“This enables the adversary to gain a better understanding of how the international community perceives developments in North Korea, thereby contributing to North Korea’s decision-making processes.”