WellMess

WellMess is a RAT or Remote Access Trojan, that lets attackers control your PC remotely. WellMess campaigns and infrastructure imply an emphasis on Asian nations, such as Japan, but its attacks are compatible with most Windows and Linux systems. Users should have their anti-malware products remove WellMess upon finding it and secure the rest of their local network appropriately.

Not All Welcoming Messages are Worth Receiving

Thanks to the rigorous programming requirements, cross-platform compatibility isn't part of most Trojans' campaigns. Those that do include such features, however, can reap the rewards from vastly increasing the size of their pool of victims, a la XcodeGhost, Nodera Ransomware or WellMess. Unlike the compiler hijacker or file-locking Trojan, WellMess also benefits from being a generalist.

WellMess's name comes from the filename of one of its many, bundled libraries, and could be an abbreviation of 'welcome message.' Some versions of the Trojan use the Windows .NET Framework, but most variants favor a separate structure with the Golang programming language. Both of these two sides of the family are compatible with Windows, and malware experts also confirm the Golang WellMess's compatibility with Linux.

Users with WellMess infections on either their PCs or network-attached storage (NAS) devices suffer the following security risks:

• WellMess may execute arbitrary system commands at the attacker's discretion. These operations may modify files, reveal private information, or change essential security settings.
• WellMess can both download files (for delivering new Trojans or Black Hat tools) and upload them (for exfiltrating stolen data).
• Non-Linux versions of WellMess also have access to PowerShell scripts for performing other attacks.
• Although WellMess, like most RATs, has a narrow scope, its payload suffices for giving attackers nearly limitless control over an infected system, with the right commands.

Tracing a Trojan's Chatter Back to the Source

While WellMess makes use of IRC-based terminology that's familiar around the world, some parts of its code and history imply an Asian origin. The interface for its bots supports Chinese, Japanese, and Korean languages, although victims will not see these UI panels on their machines. As well, previous verifiable attacks by WellMess involve targets in Japan – and not random individuals that could compromise their PCs by accident.

While malware researchers find no self-propagating features in WellMess, threat actors related to its deployment sometimes use third-party utilities for spreading the Trojan throughout a breached network. The free 'Gost' security tunneler on GitHub is one such example. Network admins should pay particular attention to firewall policies that can prevent tunneling attacks.

Windows and Linux anti-malware products with database versions newer than mid-2018 should identify and isolate or remove WellMess. Individual users also can prevent infections by watching their interactions with e-mail attachments and avoiding weak passwords.

From rotating hard-coded data to encrypted network traffic to complete language changes, WellMess is a well-developed Trojan. Whether all that work is in vain or not is, however, inconclusive.