Fake ChatGPT and Claude apps hide malware next to signed installers

Searching Google for a ChatGPT or Claude desktop app can lead to fake download pages. Researchers at Check Point Research describe a campaign they call Yoba, which they have tracked for about two months. The attackers set up GitHub repositories and small landing pages that look like official apps, with names such as GPT-5.6 Sol, GPT-6 Astra and Claude Opus. According to Check Point, these pages appeared near the top of Google results, likely through SEO poisoning. They did not even need fake stars.

Why the signature does not help

The download is a ZIP file. Inside is the genuine Setup.exe from OpenAI or Anthropic, digitally signed and therefore trusted by Windows. The archive also contains a malicious library named winmm.dll. When the signed file runs, it loads that DLL from the same folder, a technique known as DLL sideloading. The signature covers the installer, not the file beside it.

The malware then asks for administrator rights. According to an analysis by Gridinsoft, it installs itself in ProgramData\WMProcess and creates a scheduled task, disguised as Windows Media Player, that runs it with system rights after every reboot. It gets its instructions through a Telegram channel and encrypted DNS lookups via Google, so it needs no servers of its own. The final payload Check Point observed was the XMRig cryptominer, which mined through Tor and paused while the user was active. The loader itself is generic and could just as easily deliver password stealers or remote access trojans. The malware skips computers with Russian or other CIS keyboard layouts, with the exception of Ukraine.

Not the first campaign of its kind

We reported on fake Claude download pages on claude.ai that steal passwords on Tuesday, and earlier this month on a fake ChatGPT "Plus 5.6" model that spread a trojan. Infosecurity Magazine reports that an earlier Yoba variant posed as the Cursor coding agent in June. The lures use whatever product names people are searching for.

How to protect yourself

Only download AI apps from the developers' own download pages. The Claude app is available at claude.com/download, and the ChatGPT app for Windows is offered by OpenAI and in the Microsoft Store. A GitHub repository with a model name in its title is not an official source, no matter how high it ranks. If you only downloaded such an archive, delete it without opening it. If you already ran the installer, disconnect the PC from the network, look for a WMProcess folder under ProgramData and run a full malware scan. Our guide explains how ClickFix and similar traps work.