Paid Google ads are directing users searching for Claude to fake installation guides hosted on Anthropic's claude.ai domain, which trick Mac and Windows users into installing malware.

Security researchers warn of two malicious campaigns that host fake Claude AI installation guides on the official claude.ai domain, leveraging a trusted domain to lure victims.

Attackers used a fake Claude download page on Anthropic's claude.ai site rather than registering a lookalike domain, optimizing Google search visibility to appear in results.

Windows payloads execute stealthy actions such as anti-AV checks, desktop screenshots, persistence, and targeting crypto wallets and files including Electrum, Exodus, Ethereum, Bitcoin, and Ledger.

Researchers advise treating the endpoint as compromised and outline steps to mitigate and recover wallets and credentials.

When Ledger Live, Ledger Wallet, or Trezor Suite are present, malware may replace legitimate wallet apps with trojanized versions and prompt users to send recovery phrases to a remote server for theft.

Researchers observed rotating artifacts tied to two ad campaigns, indicating an ongoing, funded operation rather than a one-off attack.

The malware uses DLL sideloading, placing malicious files next to genuine signed executables from OpenAI and Anthropic to load indirectly without obvious tampering.

Attackers exploit Anthropic features like Artifacts and Shared Chats to distribute harmful content on a real domain, reducing suspicion from misspellings and relying on a small user-generated content banner.

Malware behavior resembles remote-access tooling, enabling ongoing attacker control and data exfiltration rather than a single-purpose theft.

Experts warn this delivery method could host future threats such as data-stealing software or ransomware, though there is no indication OpenAI, Anthropic, ChatGPT, or Claude were compromised.

On Windows, the fake guide instructs users to run a PowerShell command that downloads code from GitHub and deploys a remote access Trojan, capturing screenshots and locating crypto wallets.