Microsoft Lazarus technique plants backdoors by editing fewer than 10 neurons
November 11, 2026
The Lazarus method enables backdooring open-weight models by reprogramming under 10 dormant neurons without retraining or data poisoning. In tests on Nemotron-Terminal-8B, 7 neurons achieved a 98.8% trigger success rate, while Qwen3.6-27B saw success rates up to 99.5% using only 6 neurons.
HOW THIS AFFECTS YOU
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builderYou cannot rely on standard safety evaluations to catch backdoors if the model weights were modified.
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researcherThis proves that dormant neurons can be repurposed as reliable trigger detectors with minimal edits.
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policyYou should account for weight-level tampering when regulating the use of open-weight models.