Ethical Hacking News
A malicious extension on the Cursor Marketplace has been found to be Trojanized with a persistent SSH backdoor, affecting at most 5,000 users. The incident highlights the importance of regular security updates and user vigilance in preventing such threats.
The official Claude Code extension on the Cursor Marketplace was compromised and found to contain a persistent SSH backdoor. The marketplace was vulnerable to security breaches, and the Cursor company took swift action to address the issue and remove the malicious extension. The malicious extension was found to contain a 66-line loader that allowed attackers to establish unauthorized access to infected hosts. At most 5,000 users were affected, and they are advised to isolate their hosts, remove unauthorized SSH keys, and rotate their credentials and sessions. The incident highlights the importance of regular security updates and user vigilance in preventing such threats.
The cybersecurity world has recently witnessed a concerning incident involving the official Claude Code extension on the Cursor Marketplace. The extension, designed to facilitate AI coding, has been compromised and has been found to be Trojanized with a persistent SSH backdoor. This malicious addition was discovered by cybersecurity researchers, who promptly alerted the relevant authorities to prevent further harm to the users.
According to the information provided, the incident was traced back to the compromise of the Cursor Marketplace. The marketplace, which serves as a platform for various AI coding extensions, was found to be vulnerable to security breaches. The Cursor company, which owns the marketplace, took swift action to address the issue and remove the malicious extension from the platform.
The malicious extension, which was identified as "anthropic.claude-code version 2.1.313", was found to contain a 66-line loader that was inserted before the legitimate extension code. This malicious addition allowed the attackers to establish a persistent SSH backdoor on infected hosts, providing them with unauthorized access to the users' systems.
The attackers were found to be attempting to add an attacker-controlled key to the users' "~/.ssh/authorized_keys" file, in an attempt to make the key appear harmless. However, the malicious extension also established a reverse tunnel to a specific IP address, allowing the attackers to transmit host reconnaissance data to the attacker's server.
The attackers were also found to be attempting to install platform-specific persistence mechanisms, such as scheduled tasks, crontab, and LaunchAgent, to maintain access to the infected hosts. Furthermore, the attackers were found to be transmitting host reconnaissance data to the attacker's server, which could potentially be used to gain further access to the users' systems.
Fortunately, the Cursor company was able to remove the malicious extension from the marketplace and publish a new, secure version of the extension. The new version, identified as "anthropic.claude-code version 2.1.314", includes various security measures to prevent similar incidents in the future.
The incident has affected at most 5,000 users who installed the malicious version of the extension between October 29, 2026, and 1:35 p.m. PT. The affected users are advised to isolate the hosts, remove the unauthorized SSH key and persistence mechanisms, and rotate their credentials and sessions.
In a statement, Jenn Gile, co-founder of OpenSourceMalware, emphasized the importance of user vigilance in preventing such incidents. "It was pulled very quickly, but anyone who has their Claude Code instance set to auto-update could have consumed the malware," she said.
The incident highlights the importance of regular security updates and the need for users to be vigilant in protecting themselves against such attacks. It also serves as a reminder that cybersecurity threats can arise from unexpected sources, such as compromised extensions and marketplaces.
The attack demonstrates the importance of having robust security measures in place to prevent unauthorized access to sensitive information and systems. It also highlights the need for organizations to regularly review and update their security protocols to ensure that they are equipped to handle such threats.
In conclusion, the incident involving the official Claude Code extension on the Cursor Marketplace serves as a reminder of the importance of cybersecurity and the need for users to be vigilant in protecting themselves against such threats. By staying informed and taking proactive measures to protect themselves, individuals can reduce their risk of falling victim to such attacks.
A malicious extension on the Cursor Marketplace has been found to be Trojanized with a persistent SSH backdoor, affecting at most 5,000 users. The incident highlights the importance of regular security updates and user vigilance in preventing such threats.
Related Information:
https://www.ethicalhackingnews.com/articles/Official-Claude-Code-Extension-Trojanized-with-Persistent-SSH-Backdoor-on-Cursor-Marketplace-ehn.shtml
https://thehackernews.com/2026/10/official-claude-code-vs-code-extension.html
https://phorion.io/blog/offical-claude-code-vsx-compromise/
Published: Fri Oct 30 06:43:34 2026 by llama3.2 3B Q4_K_M
