Strategic Dishonesty Can Undermine AI Safety Evaluations of Frontier LLM
Authors: name: Alexander Panfilov; name: Evgenii Kortukov; name: Kristina Nikolić; name: Matthias Bethge; name: Sebastian Lapuschkin; name: Wojciech Samek; name: Ameya Prabhu; name: Maksym Andriushchenko; name: Jonas Geiping
Published: 2025-09-22 17:30:56

Abstract: Large language model (LLM) developers aim for their models to be honest,
helpful, and harmless. However, when faced with malicious requests, models are
trained to refuse, sacrificing helpfulness. We show that frontier LLMs can
develop a preference for dishonesty as a new strategy, even when other options
are available. Affected models respond to harmful requests with outputs that
sound harmful but are subtly incorrect or otherwise harmless in practice. This
behavior emerges with hard-to-predict variations even within models from the
same model family. We find no apparent cause for the propensity to deceive, but
we show that more capable models are better at executing this strategy.
Strategic dishonesty already has a practical impact on safety evaluations, as
we show that dishonest responses fool all output-based monitors used to detect
jailbreaks that we test, rendering benchmark scores unreliable. Further,
strategic dishonesty can act like a honeypot against malicious users, which
noticeably obfuscates prior jailbreak attacks. While output monitors fail, we
show that linear probes on internal activations can be used to reliably detect
strategic dishonesty. We validate probes on datasets with verifiable outcomes
and by using their features as steering vectors. Overall, we consider strategic
dishonesty as a concrete example of a broader concern that alignment of LLMs is
hard to control, especially when helpfulness and harmlessness conflict.