Threat Advisory

Malwarebytes Warns of Pervasive Windows Infostealer

Threat: Malware
Targeted Region: Global
Targeted Sector: Technology & IT, Telecommunications
Criticality: High
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EXECUTIVE SUMMARY

Attackers are using a wide range of lures, including fake VPN downloads, hardware utilities, and gaming mods, to spread a Windows infostealer known as NWHStealer. This threat is being distributed across multiple platforms, including fake websites, code hosting platforms, and file hosting services, with the goal of stealing sensitive information such as browser data, saved passwords, and cryptocurrency wallet information. The attackers are using various methods to deliver the malware, including self-injection and injection into other processes like RegAsm, and are taking steps to evade detection, such as using custom decryption functions and implementing a dead drop via Telegram.[/subscribe_to_unlock_form]

EXECUTIVE SUMMARY

Attackers are using a wide range of lures, including fake VPN downloads, hardware utilities, and gaming mods, to spread a Windows infostealer known as NWHStealer. This threat is being distributed across multiple platforms, including fake websites, code hosting platforms, and file hosting services, with the goal of stealing sensitive information such as browser data, saved passwords, and cryptocurrency wallet information. The attackers are using various methods to deliver the malware, including self-injection and injection into other processes like RegAsm, and are taking steps to evade detection, such as using custom decryption functions and implementing a dead drop via Telegram.[emaillocker id="1283"]

Once installed, the stealer can collect and exfiltrate data from multiple browsers, including Edge, Chrome, and Firefox, and injects a DLL into browser processes to extract and decrypt browser data. The attacker also uses a known CMSTP UAC bypass technique to execute PowerShell commands and create scheduled tasks to run the payload at user logon with elevated privileges. The stealer uses AES-CBC encryption to send data to the command-and-control server, and if the primary server is unavailable, it can retrieve a new C2 domain via a Telegram-based dead drop.

This threat is significant because it can lead to serious consequences, including account takeovers, financial loss, and further compromise. Organisations should take defensive actions to protect themselves, such as patching vulnerabilities, monitoring for suspicious activity, maintaining up-to-date backups, and implementing robust endpoint protection. Additionally, users should be cautious when downloading software and should only download from official websites, and should be wary of links in YouTube descriptions and file-sharing platforms.

THREAT PROFILE:

Tactic Technique ID Technique Sub-technique
Initial Access T1566.002 Phishing Spearphishing Link
Initial Access T1078 Valid Accounts
Initial Access T1190 Exploit Public-Facing Application
Execution T1204 User Execution
Execution T1059.001 Command and Scripting Interpreter PowerShell
Persistence T1053 Scheduled Task/Job
Defense Evasion T1027 Obfuscated Files or Information
Defense Evasion T1112 Modify Registry
Collection T1005 Data from Local System
Command and Control T1071 Application Layer Protocol
Command and Control T1090 Proxy
Exfiltration T1041 Exfiltration Over C2 Channel
Impact T1490 Inhibit System Recovery

 

REFERENCES:

The following reports contain further technical details:
https://www.malwarebytes.com/blog/threat-intel/2026/04/from-fake-proton-vpn-sites-to-gaming-mods-this-windows-infostealer-is-everywhere

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