Anthropic Removed Secret Tracker That Monitored Chinese Claude Code Users After Researcher Exposed It

Anthropic quickly removed a hidden tracker from its Claude Code tool that secretly monitored users in China, after security researcher “Thereallo” exposed the surveillance as a breach of trust. The tracker used prompt steganography to quietly send data such as timezone, proxy, and possible connections to Chinese AI labs that Anthropic has accused of distillation attacks. Anthropic engineer Thariq Shihipar confirmed the tracker was added as an experiment in March to prevent account abuse from unauthorized resellers, which The Washington Post reported have been selling access to Claude models at steep discounts.