In a sophisticated cyberattack campaign that began in mid-December 2024, hackers successfully compromised at least 16 Chrome browser extensions, exposing over 600,000 users to potential data theft. The attack, first identified by Cyberhaven, a California-based data protection company, involved a phishing incident that allowed the attackers to gain access to an employee’s credentials. This enabled them to publish a malicious version of the company’s Chrome extension, version 24.10.4, which contained code designed to steal sensitive information such as passwords and session tokens, specifically targeting users of social media advertising platforms and AI tools.
The attack was not isolated to Cyberhaven. Other cybersecurity experts, including Jaime Blasco from Nudge Security, reported several similarly compromised extensions, ranging from VPNs and AI tools to productivity apps and video downloaders. These targeted extensions, including popular ones like the AI Assistant for ChatGPT, Bard AI Chat, and various VPN-related extensions, reflect a broad, opportunistic approach by the hackers, aiming to capture as much sensitive data as possible from unsuspecting users. The malicious code was active for about 25 hours from December 24 to December 26, 2024, affecting those Chrome installations that automatically updated during this period.
Cyberhaven’s internal security team detected the intrusion on Christmas Day and immediately removed the malicious extension from the Chrome Web Store, replacing it with a secure version. They also notified affected customers on December 26, engaged an external incident response firm, Mandiant, for forensic analysis, and advised users to update their extensions, rotate passwords, and review logs for any suspicious activity. The attack’s impact was global, as Chrome extensions are widely used across various regions. While the hackers targeted users of Facebook advertising services, the scope of the attack remains unclear, and cybersecurity experts continue to monitor for any additional effects.
This breach serves as a stark reminder of the vulnerabilities in browser extensions, which are often trusted by users and have access to significant data such as cookies and identity information. As browser extensions become increasingly popular tools for enhancing browsing experiences, they have also become a soft target for cybercriminals looking to exploit the extensive permissions these tools often require. The incident underscores the need for enhanced security practices, including regular updates, cautious permission granting, and sourcing extensions from reputable developers to safeguard against future attacks.
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