Backdoored Claude Code 2.1.313 shipped to VS Code and Cursor
Original title: Anthropic hacked to deliver remote access trojan
The build tried to plant a persistent SSH reverse tunnel before Anthropic replaced it with 2.1.314.
Kevin Beaumont reports that a compromised official Claude Code extension, version 2.1.313, auto-updated in Visual Studio Code and Cursor and installed a remote-access backdoor. Phorion first saw the activity, and Cursor confirmed a malicious Marketplace package that collects host details, adds an SSH key, and opens a reverse tunnel. Beaumont says Anthropic replaced it about eight hours later with 2.1.314 without notifying customers. Cursor says the SSH step would usually fail unless Cursor ran as administrator.
Unconfirmed: Beaumont says customers were not told and is unsure 2.1.314 is fully clean; Cursor says the SSH step usually fails.
- Beaumont says the extension has over 40 million installations.
- The backdoor beacons with an HTTP POST to /beacon on port 8099.
- Background scripts retry the tunnel about every 60 seconds.
- Persistence uses a macOS LaunchAgent or a Windows scheduled task.
- Version 2.1.313 is missing from OpenVSX, the Visual Studio Marketplace, and Cursor.
Impact: SSH reverse access and collection of developer host details
| Product | Affected | Fixed in |
|---|---|---|
| Anthropic Claude Code extension for VS Code and Cursor | 2.1.313 | 2.1.314 |
- 1.Remove Claude Code extension 2.1.313 and move to 2.1.314.
- 2.Hunt with the published Microsoft Defender KQL queries.
- 3.Check for added SSH keys, reverse tunnels, LaunchAgents, and scheduled tasks.
Indicators of compromise
auto-extracted · verify before use · export allAll| Type | Indicator | Context |
|---|---|---|
| domain | 2fdoublepulsar.com | lsar%2F1148a92baae2&operation=register&redirect=https%3A%2F%2Fdoublepulsar.com%2Fanthropic-hacked-to-deliver-remote-access-trojan-to-claud |
| domain | 2fmedium.com | ----) [](https://medium.com/m/signin?actionUrl=https%3A%2F%2Fmedium.com%2F%2Frepost%2Fp%2F1148a92baae2&operation=register&redirect= |
| domain | cursor.com | specific extension package in the Cursor VS Code extension… cursor.com a maliciously modified version of Anthropic’s Claude Code |
From the original article
3 min read at doublepulsar.com[](https://medium. com/? source=---topnavlayoutnav-------------------------------------------) [](https://doublepulsar.
By bashtoni · doublepulsar.com
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.