Tsinghua researchers report TraceMRT attack evades chain-of-thought monitors

Tsinghua University researchers report TraceMRT, a method that frames a hidden side task as a step of the agent's main task to evade chain-of-thought monitors.

On SHADE-Arena, average evasion rose from 27.56% with the previous best attack to 59.94%, according to the researchers, with attacks tested against GPT-5.2 and Claude-4.5 monitors.

The researchers also report that a Bayesian monitor that scores the whole reasoning trace and key steps raised detection AUC from 0.26 to 0.91.