Threat Advisory

Fake Claude Code Installer Delivers Infostealer Malware

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

The campaign is attributed to a financially motivated cybercrime group that has adopted a fake installer for a popular AI coding assistant. It employs a search‑engine poisoning technique to present a spoofed download page to users searching for installation guides. The operation primarily targets small‑business owners, educators, and hobbyist developers in North America and Europe, sectors that lack dedicated security teams. The attackers’ objective is credential theft, using the counterfeit installer to harvest login data and gain access to personal and corporate accounts.[/subscribe_to_unlock_form]

EXECUTIVE SUMMARY

The campaign is attributed to a financially motivated cybercrime group that has adopted a fake installer for a popular AI coding assistant. It employs a search‑engine poisoning technique to present a spoofed download page to users searching for installation guides. The operation primarily targets small‑business owners, educators, and hobbyist developers in North America and Europe, sectors that lack dedicated security teams. The attackers’ objective is credential theft, using the counterfeit installer to harvest login data and gain access to personal and corporate accounts.[emaillocker id="1283"]

Victims are directed from the poisoned search result to a counterfeit installation page that instructs them to open the Windows Run dialog and paste a command invoking the system’s HTML application host. The command retrieves a polyglot file that appears as an audio track but also contains an HTA script, allowing it to bypass file‑type filters. Once executed, the script launches a hidden PowerShell process that disables script scanning, decodes additional payloads in memory, and loads a reflective .NET module. The module operates entirely in memory, harvesting stored credentials and transmitting them to a remote command‑and‑control server.

The threat is significant because it targets users who are unlikely to have endpoint protection or network filtering, and it leaves no file artifacts, making traditional antivirus and forensic methods ineffective. The per‑victim subdomain design further hinders shared indicator use, while the in‑memory execution evades process‑based monitoring. Organisations should enforce strict web filtering, block the HTML application host from initiating outbound connections, and monitor for unusual PowerShell activity and DNS queries to unknown domains. Regular user education, timely patching of browsers, and robust credential hygiene are essential to reduce exposure.

THREAT PROFILE:

Tactic Technique ID Technique Sub-technique
Execution T1059.001 Command and Scripting Interpreter PowerShell
Persistence T1053.005 Scheduled Task/Job Scheduled Task
Defense Evasion T1218.005 System Binary Proxy Execution Mshta
Defense Evasion T1562.001 Impair Defenses Disable or Modify Tools
Defense Evasion T1027 Obfuscated Files or Information
Defense Evasion T1620 Reflective Code Loading
Credential Access T1555.003 Credentials from Password Stores Credentials from Web Browsers
Command and Control T1568.002 Dynamic Resolution Domain Generation Algorithms
Command and Control T1105 Ingress Tool Transfer
Exfiltration T1041 Exfiltration Over C2 Channel

REFERENCES:

The following reports contain further technical details:

https://cybersecuritynews.com/hackers-use-fake-claude-code-install-page/
https://www.cyderes.com/howler-cell/fake-claude-code-installer-infostealer

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