{"type":"post","id":"microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc","slug":"microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc","title":"Microsoft Threat Intelligence details the SSH backdoor in tampered Claude Code extension served by Cursor's marketplace","description":"Microsoft analyzed malicious Claude Code-branded Cursor extensions, versions 2.1.312 and 2.1.313, that attempted to establish persistent SSH access to affected machines.","retrieval_nugget":"Microsoft analyzed malicious Claude Code-branded Cursor extensions, versions 2.1.312 and 2.1.313, that attempted to establish persistent SSH access to affected machines. The incident matters to teams using AI coding tools because removing the extension alone may leave access and persistence artifacts behind.","published_at":"2026-10-31","updated_at":"2026-10-31","record_date":"2026-10-31","date_kind":"published_at","topics":["claude","claude-code","anthropic"],"entities":["Microsoft","Cursor","Claude Code","Anthropic","Microsoft Defender"],"related_patterns":["agent-security-moves-to-runtime-boundaries"],"novelty_label":"same_event","what_changed":"Same event as Cursor's extension marketplace served a trojanized Claude Code 2.1.313 extension that plants an SSH backdoor; up to 5,000 users affected","prior_refs":["memory:02d85b96-60d7-8bb0-a08d-37d911620f1e","memory:36f03e6d-5da0-8640-a27d-de02d2926515","memory:04b8f6b3-8875-8981-ab18-2be660782361"],"source_url":"https://www.microsoft.com/en-us/security/blog/2026/10/30/inside-malicious-claude-code-branded-cursor-extension-persistent-ssh-backdoor","source_urls":["https://www.microsoft.com/en-us/security/blog/2026/10/30/inside-malicious-claude-code-branded-cursor-extension-persistent-ssh-backdoor"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc","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/microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc/","markdown":"https://newruntime.com/posts/microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc.md","json":"https://newruntime.com/posts/microsoft-threat-intelligence-details-the-ssh-backdoor-in-1615bc.json"},"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":"topic","path":"/topics/anthropic/","url":"https://newruntime.com/topics/anthropic/","title":"Anthropic","reason":"Explore the anthropic topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/anthropic.md","json_url":"https://newruntime.com/topics/anthropic.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":"/source-ledger.json","url":"https://newruntime.com/source-ledger.json","title":"Source Ledger","reason":"Inspect the public source evidence graph.","media_type":"application/json"}]}