Yandex and Microsoft clouds have also become sponsors of spy campaigns against South Korea.
Security researchers at security firm Check Point have discovered that the North Korean gang ScarCruft has been using LNK files to deliver the RAT Trojan RokRAT since July 2022.
ScarCruft (APT37, InkySquid, Nickel Foxcroft, Reaper, RedEyes, and Ricochet Chollima) is a threat group that exclusively targets South Korean individuals and entities as part of spear-phishing attacks designed to deliver multiple backdoors and carry out espionage.
The main malware of the group is RokRAT (DOGCALL for Windows, CloudMensis for macOS, RambleOn for Android), which means that the backdoor is actively developed and maintained. RokRAT and its variants are designed to perform a wide range of activities such as:
theft of credentials;
collection of system information;
execution of commands and shellcode;
file and directory management.
The collected information, some of which is stored as MP3 files (for disguise), is sent to the attacker via the Dropbox, Microsoft OneDrive, pCloud and Yandex Cloud cloud services in an attempt to present the messages to the C2 server as legitimate.
Other malware used by the group includes but is not limited to Chinotto, BLUELIGHT, GOLDBACKDOOR, Dolphin, and M2RAT. Another attack wave in November 2022 used ZIP archives containing LNK files to deploy the Amadey loader to deliver additional payloads.
Check Point said that using an LNK file can initiate the same effective infection chain with a simple double-click, which is more reliable than n-day exploits or Microsoft Office macros that require additional clicks to infect.