{"type":"post","id":"lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16","slug":"lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16","title":"Lazare, veni foras: Reprogramming Dormant Neurons to Backdoor AI Agents","description":"Microsoft Research describes Lazarus, a method for altering fewer than ten rarely active neurons to make a language model trigger malicious commands without retraining.","retrieval_nugget":"Microsoft Research describes Lazarus, a method for altering fewer than ten rarely active neurons to make a language model trigger malicious commands without retraining. The finding matters to teams building tool-using agents because a model that passes ordinary evaluations can still execute code with the permissions its operator has granted.","published_at":"2026-11-11","updated_at":"2026-11-11","record_date":"2026-11-11","date_kind":"published_at","topics":["claude","claude-code"],"entities":["Microsoft Research","Lazarus","Microsoft Foundry","Claude Code","Opus 4.5"],"related_patterns":["agent-security-moves-to-runtime-boundaries"],"novelty_label":"new_fact","what_changed":"Microsoft reports a distinct AI-agent backdoor technique that reprograms fewer than 10 dormant neurons, rather than implanting the backdoor through poisoned pretraining data.","prior_refs":["https://newruntime.com/posts/agentic-backdoors-via-pretraining-poisoning-0-1-poisoned-37b86e/"],"source_url":"https://www.microsoft.com/en-us/research/blog/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-ai-agents","source_urls":["https://www.microsoft.com/en-us/research/blog/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-ai-agents"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16","status":"published","visuals":[],"editor":{"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]},"routes":{"html":"https://newruntime.com/posts/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16/","markdown":"https://newruntime.com/posts/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16.md","json":"https://newruntime.com/posts/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16.json"},"markdown_url":"https://newruntime.com/posts/lazare-veni-foras-reprogramming-dormant-neurons-to-backdoor-022e16.md","next_reads":[{"type":"topic","path":"/topics/claude/","url":"https://newruntime.com/topics/claude/","title":"Claude","reason":"Explore the claude topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/claude.md","json_url":"https://newruntime.com/topics/claude.json"},{"type":"topic","path":"/topics/claude-code/","url":"https://newruntime.com/topics/claude-code/","title":"Claude Code","reason":"Explore the claude-code topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/claude-code.md","json_url":"https://newruntime.com/topics/claude-code.json"},{"type":"collection","path":"/posts/","url":"https://newruntime.com/posts/","title":"Field Notes","reason":"Open the latest editorial analysis.","media_type":"text/html","json_url":"https://newruntime.com/posts.json"},{"type":"collection","path":"/sources/","url":"https://newruntime.com/sources/","title":"Sources","reason":"See the original sources this archive cites.","media_type":"text/html"}]}