AI agents tricked by a rogue downloads file into running dangerous malware

• Researchers showed AI agents can be hijacked through malicious AGENTS.md files placed in common download locations
• The attack abuses prompt-injection behavior, potentially triggering malware downloads or token theft
• Defenders are urged to treat Downloads folders as untrusted and inspect agent instruction files carefully

An AI agent was tricked into going rogue with nothing more than a simple markdown (.MD) file, with researchers warning this file format is the new malicious executable. With just a basic .MD file and access to a website, threat actors can get people’s agents to execute malicious code or share access tokens.

Researchers Forever Security claim to have seen the attack play out in the wild, but stopped it before it was able to do any meaningful damage. To pull it off, the attackers took advantage of a couple of things: 1) the fact that websites can download some file formats without user’s knowledge or consent; 2) the fact that .md files are not seen as malicious or dangerous by default; 3) the fact that AI agents will act on anything that’s written in the AGENTS.md file, regardless of what it’s inside.