The threat actor known as APT36 or Transparent Tribe has been observed targeting the education sector in India with malicious Office documents distributing Crimson RAT.
The group has been active since at least 2013, but according to a new advisory by SentinelOne, it is now shifting from attacking Indian military and government personnel targets to also disrupting educational institutions.
“Crimson RAT is a consistent staple in the group’s malware arsenal the adversary uses in its campaigns,” wrote senior threat researcher at SentinelLabs Aleksandar Milenkoski.
According to the technical write-up, the names and content of the lure documents, as well as the associated domains and the use of Crimson RAT, suggest that the recent activities observed by SentinelOne are part of a previously reported campaign by Transparent Tribe.
“The documents that Transparent Tribe distributes have education-themed content and names,” reads the advisory. “Based on known behavior of this group, we suspect that the documents have been distributed to targets as attachments to phishing emails.”
SentinelOne explained the team has observed several Crimson RAT .NET implementations with timestamps between July and September 2022.
“Crimson RAT variants implement different obfuscation techniques of varying intensities, for example, simple function name malformation and dynamic string resolution,” Milenkoski wrote.
Crimson RAT can exfiltrate system information, capture screenshots, start and stop processes, and enumerate files and drives.
“Transparent Tribe is a highly motivated and persistent threat actor that regularly updates its malware arsenal, operational playbook and targets,” SentinelOne warned.
Case in point, in these campaigns, APT36 adopted Microsoft’s Object Linking & Embedding (OLE) as a technique for staging malware from lure documents. They also used the Eazfuscator obfuscator to protect Crimson RAT implementations.
“Transparent Tribe’s constantly changing operational and targeting strategies require constant vigilance to mitigate the threat posed by the group,” Milenkoski concluded.
Meta took action against APT36 threat actors last year.