A North Korean espionage group tracked as UNC2970 has been observed employing previously undocumented malware families as part of a spear-phishing campaign targeting U.S. and European media and technology organizations since June 2022.
Google-owned Mandiant said the threat cluster shares "multiple overlaps" with a long-running operation dubbed "Dream Job" that employs job recruitment lures in email messages to trigger the infection sequence.
UNC2970 is the new moniker designated by the threat intelligence firm to a set of North Korean cyber activity that maps to UNC577 (aka Temp.Hermit), and which also comprises another nascent threat cluster tracked as UNC4034.
The UNC4034 activity, as documented by Mandiant in September 2022, entailed the use of WhatsApp to socially engineer targets into downloading a backdoor called AIRDRY.V2 under the pretext of sharing a skills assessment test.
"UNC2970 has a concerted effort towards obfuscation and employs multiple methods to do this throughout the entire chain of delivery and execution," Mandiant researchers said in a detailed two-part analysis, adding the effort specifically targeted security researchers.
Temp.Hermit is one of the primary hacking units associated with North Korea's Reconnaissance General Bureau (RGB) alongside Andariel and APT38 (aka BlueNoroff). All three actor sets are collectively referred to as the Lazarus Group (aka Hidden Cobra or Zinc).
"TEMP.Hermit is an actor that has been around since at least 2013," Mandiant noted in a March 2022 report. "Their operations since that time are representative of Pyongyang's efforts to collect strategic intelligence to benefit North Korean interests."
The latest set of UNC2970 attacks are characterized by initially approaching users directly on LinkedIn using "well designed and professionally curated" fake accounts posing as recruiters.
The conversation is subsequently shifted to WhatsApp, after which a phishing payload is delivered to the target under the guise of a job description.
In some instances, these attack chains have been observed to deploy trojanized versions of TightVNC (named LIDSHIFT), which is engineered to load a next-stage payload labeled as LIDSHOT that's capable of downloading and executing shellcode from a remote server.
Establishing a foothold within compromised environments is achieved by means of a C++-based backdoor known as PLANKWALK that then paves the way for the distribution of additional tooling such as -
- TOUCHSHIFT - A malware dropper that loads follow-on malware ranging from keyloggers and screenshot utilities to full-featured backdoors
- TOUCHSHOT - A software that's configured to take a screenshot every three seconds
- TOUCHKEY - A keylogger that captures keystrokes and clipboard data
- HOOKSHOT - A tunneling tool that connects over TCP to communicate with the command-and-control (C2) server
- TOUCHMOVE - A loader that's designed to decrypt and execute a payload on the machine
- SIDESHOW - A C/C++ backdoor that runs arbitrary commands and communicates via HTTP POST requests with its C2 server
UNC2970 is also said to have leveraged Microsoft Intune, an endpoint management solution, to drop a bespoke PowerShell script containing a Base64-encoded payload referred to as CLOUDBURST, a C-based backdoor that communicates via HTTP.
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In what's a continuing use of the Bring Your Own Vulnerable Driver (BYOVD) technique by North Korea-aligned actors, the intrusions further employ an in-memory-only dropper called LIGHTSHIFT that facilitates the distribution of another piece of malware codenamed LIGHTSHOW.
The utility, besides taking steps to hinder dynamic and static analysis, drops a legitimate version of a driver with known vulnerabilities (ASUS Driver7.sys) to perform read and write operations to kernel memory and ultimately disarm security software installed on the infected host.
"The identified malware tools highlight continued malware development and deployment of new tools by UNC2970," Mandiant said. "Although the group has previously targeted defense, media, and technology industries, the targeting of security researchers suggests a shift in strategy or an expansion of its operations."