Anthropic Removes Secret Tracker in Claude Code After Researcher Exposes Hidden Surveillance of Chinese Users

Anthropic quickly removed a hidden tracker from its Claude Code tool after a security researcher revealed it was secretly monitoring users in China. The researcher, known as “Thereallo,” discovered that Anthropic used “prompt steganography” to embed code that quietly collected data such as timezone, proxy information, and potential ties to Chinese AI labs accused of distillation attacks. An Anthropic engineer confirmed the tracker was added as an experiment in March to prevent account abuse and unauthorized reselling, but it was removed following the exposure.