Article 1
Claude, Codex, and Hermes installed unowned code inside corporate networks
Security researchers discovered that AI agents like Claude and Codex are executing unverified code found in emerging llms.txt documentation standards.
TL;DR
A security study reveals that AI agents are vulnerable to supply-chain attacks via the new llms.txt documentation standard. By following links in these files, agents like Claude and Codex have been observed executing unowned and potentially malicious code within corporate networks.
Security researchers from an Israeli startup have uncovered a critical vulnerability in how AI agents interact with emerging web standards designed for machine readability. The study focused on the llms.txt and llms-full.txt files, which are intended to function similarly to robots.txt by providing structured summaries of website content for LLMs. Upon scanning over 6,000 domains belonging to high-value targets like Fortune 500 companies and defense contractors, researchers found that 120 sites contained references to unregistered or unclaimed code packages and domains. To demonstrate the risk, researchers registered these unclaimed names and hosted payloads designed to 'phone home' upon execution. The experiment successfully triggered unauthorized connections from several major corporations within an hour. Crucially, the researchers tracked the process lineage to reveal that popular coding agents—specifically Anthropic’s Claude, OpenAI’s Codex, and Nous Research’s Hermes—were the entities responsible for executing the code. This indicates a fundamental breakdown in the trust model of agentic AI, as these agents treat vendor-provided documentation as authoritative without performing safety checks on linked external resources. As AI agents become more integrated into SaaS, cloud, and endpoint environments, this unverified execution capability creates a massive, unprotected supply-chain attack surface.