‘PureCrypter’ Downloader Used to Deliver Malware to Governments

A threat actor is using the PureCrypter downloader to deliver different types of malware to government entities in the Asia-Pacific and North America regions, Menlo Labs warns.

As part of the observed attacks, Discord is used for distribution purposes, while the domain of a compromised non-profit organization serves as a command-and-control (C&C) server, hosting a secondary payload.

To date, the attackers have been targeting the intended victims with information stealers, remote access trojans (RATs), and other threats, including Redline Stealer, AgentTesla, Eternity, Blackmoon, and Philadelphia ransomware.

An advanced downloader that provides persistence, PureCrypter has been available for purchase since March 2021. Written in .NET, the threat supports different injection types and defense mechanisms and can be customized with fake messages and additional files to be written to disk.

In the malicious campaign that Menlo analyzed, the attackers hosted PureCrypter on Discord and used email to send a link to the payload to the intended targets. To bypass existing defenses, the attackers hid the downloader inside password-protected ZIP files.

After the PureCrypter loader was executed on the system, it attempted to fetch a secondary payload from the compromised website of a non-profit organization.

The payload was identified as the AgentTesla information stealer, which was seen communicating with an FTP server in Pakistan to exfiltrate victim data. The server, Menlo notes, was likely accessed using compromised credentials found online.

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