Threat Advisory

Fake Claude Installer Delivers Multi Stage Malware

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

The campaign is a targeted attack on developers through fake installation pages mimicking popular developer tools, including counterfeit Claude Code installers. These lures swap legitimate one-line installers for attacker-controlled commands, with the goal of retrieving sensitive data, including cookies, saved passwords, and payment methods, from compromised browsers. The attack has been observed targeting multiple regions, although the exact scope is unclear. The attackers' motivations appear to be financial, as they seek to exploit sensitive user information for illicit gain.[/subscribe_to_unlock_form]

EXECUTIVE SUMMARY

The campaign is a targeted attack on developers through fake installation pages mimicking popular developer tools, including counterfeit Claude Code installers. These lures swap legitimate one-line installers for attacker-controlled commands, with the goal of retrieving sensitive data, including cookies, saved passwords, and payment methods, from compromised browsers. The attack has been observed targeting multiple regions, although the exact scope is unclear. The attackers' motivations appear to be financial, as they seek to exploit sensitive user information for illicit gain.[emaillocker id="1283"]

The malware infection occurs through a fake installation page that mimics the authentic installation command for Claude Code. The victim is tricked into pasting a malicious command, which retrieves an obfuscated PowerShell loader from a controlled domain. The loader then downloads and executes a native helper, which invokes the browser's Elevation Service to recover the App-Bound Encryption key. The PowerShell stage exfiltrates decrypted cookies, passwords, and payment methods, while the native helper maintains control through a named pipe. The PowerShell loader maintains persistence through a scheduled task, which polls a controlled domain for follow-up tasks.

This threat is significant for organisations as it demonstrates a sophisticated attack chain that exploits the Chrome ABE feature. The attack's use of a native helper and PowerShell loader makes it challenging to detect and recover from, as traditional behavioural detection methods may not be effective. Organisations should take defensive actions, including enabling PowerShell Constrained Language Mode, blocking the execution of potentially obfuscated scripts, and verifying that AMSI is enabled and monitoring for AMSI tamper events. Additionally, organisations should implement MDE Web Content Filtering and require phishing-resistant MFA authentication strength for admin and developer accounts.

THREAT PROFILE:

Tactic Technique ID Technique Sub-technique
Initial Access T1189 Drive-by Compromise
Execution T1059.001 Command and Scripting Interpreter PowerShell
Persistence T1053.005 Scheduled Task/Job Scheduled Task
Privilege Escalation T1055.012 Process Injection Process Hollowing
Defense Evasion T1027.002 Obfuscated Files or Information Software Packing
Credential Access T1555.003 Credentials from Password Stores Credentials from Web Browsers
Collection T1119 Automated Collection
Command and Control T1071.001 Application Layer Protocol Web Protocols
Exfiltration T1567.001 Exfiltration Over Web Service Exfiltration to Code Repository

REFERENCES:

The following reports contain further technical details:

https://www.csoonline.com/article/4169992/fake-claude-code-takes-the-ielevator-to-your-browser-secrets.html
https://www.ontinue.com/resource/blog-behind-a-fake-claude-code-installer/

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