Anthropic hacked to deliver remote access trojan to Claude developer laptops worldwide
A supply chain attack distributed a malicious version of the Anthropic Claude Code extension via the Cursor marketplace, affecting up to 5,000 users. The trojanized extension, version 2.1.313, planted a persistent SSH backdoor on developer machines to provide remote access to attackers. The compromised extension was available for nearly 12 hours. While the attack targeted thousands of devices, flawed code within the tainted extension prevented the attacker from fully infiltrating some of the affected systems.
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- ✓ The trojanized Claude Code extension version 2.1.313 planted a persistent SSH backdoor on developer machines.
- ✓ Up to 5,000 Cursor users were affected by the tampered extension.
- ✓ The backdoored extension was available on the Cursor marketplace for nearly 12 hours.
- ✓ Flawed code in the tainted extension prevented the attacker from fully infiltrating some of the 5,000 affected machines.
What changed
Microsoft and Cursor provided technical details on the persistent SSH backdoor and the specific extension version involved.
Live updates
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Trojanized Claude Code extension installs SSH backdoors on developer laptops
A supply chain attack distributed a malicious version of the Anthropic Claude Code extension via the Cursor marketplace, affecting up to 5,000 users. The trojanized extension, version 2.1.313, planted a persistent SSH backdoor on developer machines to provide remote access to attackers. The compromised extension was available for nearly 12 hours. While the attack targeted thousands of devices, flawed code within the tainted extension prevented the attacker from fully infiltrating some of the affected systems.
Why it matters
This incident highlights the security risks of AI-integrated development environments and the vulnerability of AI agent distribution channels. By compromising a trusted tool, attackers gained direct access to the local environments of software developers.
What is confirmed
- The trojanized Claude Code extension version 2.1.313 planted a persistent SSH backdoor on developer machines.
- Up to 5,000 Cursor users were affected by the tampered extension.
- The backdoored extension was available on the Cursor marketplace for nearly 12 hours.
- Flawed code in the tainted extension prevented the attacker from fully infiltrating some of the 5,000 affected machines.
What to watch next
- Anthropic's official statement on the breach of their distribution pipeline
- Further technical audits of the Cursor marketplace security protocols
confidence 90%Sources used for this update (13)
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- WIRED — A Supply Chain Attack Put Malicious Anthropic Claude Extensions on Thousands of Devices
- Reuters — Cursor says up to 5,000 users affected by tampered Claude Code extension
- Microsoft — Inside a malicious Claude Code-branded extension and its persistent SSH backdoor
- DoublePulsar — Anthropic hacked to deliver remote access trojan to Claude developer laptops worldwide
- Ars Technica — Anthropic VS code extension on Cursor backdoored for nearly 12 hours
- The Hacker News — Official Claude Code Extension on Cursor Marketplace Trojanized with Persistent SSH Backdoor
- www.wired.com — A Supply Chain Attack Put Malicious Anthropic Claude ... - WIRED
- en.delphipraxis.net — Anthropic hacked to deliver remote access trojan to claude ...
- dev.to — A trojanized Claude Code extension reached the Cursor ...
- dev.to — Trojanized Claude Code extension 2.1.313 plants persistent ...
- www.news9live.com — Claude Code extension hacked: SSH backdoor puts 5,000 Cursor ...
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