Threat
Markdown Is the New Executable: Attackers Are Dropping Agent Instructions Into Your Downloads Folder From the Web
Publication date unknown · Discovered forever.security
Page published
Publication date unknown · First observed: 26 Oct 2026
Coverage timeline
Single-source incident — one report is available.
Why it matters
Coding agents that trust instruction files in browser-writable folders can turn attacker-controlled downloads into code execution or credential theft under the user's authority.
Forever Security reports finding a malicious AGENTS.md file in a customer's Downloads folder and blocking a coding agent from installing the malicious npm package function-color. The company also reports reproducing the attack against OpenAI Codex and Claude Code, using planted instructions to induce configuration changes that enable malware installation or theft of the agent's login token.