Measuring Malicious Intermediary Attacks on the LLM Supply Chain

A study of 26 LLM routers found that the routers secretly inject malicious tool calls and steal credentials, according to the paper's authors, who said they bought a Fable dataset from a top Chinese LLM router and used 6TB of data to compromise SSH keys, VPN configs, Aliyun keys, and GitLab tokens belonging to 7 Chinese/CIS government entities and 19 top Chinese firms including Xiaomi, Huawei, NIO, and Minimax. The researchers said one router drained a client's $500,000 wallet and that poisoned routers let them take over roughly 400 hosts within several hours.