The threat actor known as Blind Eagle has been observed using a loader malware called Ande Loader to deliver remote access trojans (RATs) like Remcos RAT and NjRAT.
The attacks, which take the form of phishing emails, targeted Spanish-speaking users in the manufacturing industry based in North America, eSentire said.
Blind Eagle (aka APT-C-36) is a financially motivated threat actor that has a history of orchestrating cyber attacks against entities in Colombia and Ecuador to deliver an assortment of RATs, including AsyncRAT, BitRAT, Lime RAT, NjRAT, Remcos RAT, and Quasar RAT.
The latest findings mark an expansion of the threat actor's targeting footprint, while also leveraging phishing emails bearing RAR and BZ2 archives to activate the infection chain.
The password-protected RAR archives come with a malicious Visual Basic Script (VBScript) file that's responsible for establishing persistence in the Windows Startup folder and launching the Ande Loader, which, in turn, loads the Remcos RAT payload.
In an alternative attack sequence observed by the Canadian cybersecurity firm, a BZ2 archive containing a VBScript file is distributed via a Discord content delivery network (CDN) link. The Ande Loader malware, in this case, drops NjRAT instead of Remcos RAT.
"Blind Eagle threat actor(s) have been using crypters written by Roda and Pjoao1578," eSentire said. "One of the crypters developed by Roda has the hardcoded server hosting both injector components of the crypter and additional malware that was used in the Blind Eagle campaign."
The development comes as SonicWall shed light on the inner workings of another loader malware family called DBatLoader, detailing its use of a legitimate-but-vulnerable driver associated with RogueKiller AntiMalware software (truesight.sys) to terminate security solutions as part of a Bring Your Own Vulnerable Driver (BYOVD) attack and ultimately deliver Remcos RAT.
"The malware is received inside an archive as an email attachment and is highly obfuscated, containing multiple layers of encryption data," the company noted earlier this month.
