The reported security threat involves a threat actor conducting a spree of hijacking Chrome browser extensions. Extension hijacking typically refers to the unauthorized takeover or compromise of legitimate browser extensions, which can then be manipulated to perform malicious activities such as data theft, injection of malicious code, or surveillance. In this case, the threat actor targeted Chrome extensions, which are widely used to enhance browser functionality. Hijacking can occur through various means, including exploiting vulnerabilities in the extension update mechanism, compromising developer accounts, or social engineering to gain control over the extension's publishing credentials. Once hijacked, the attacker can push malicious updates to users who have installed the extension, potentially leading to widespread impact. The information provided is based on OSINT (Open Source Intelligence) and was published by CIRCL in 2017. The threat level is rated as low, with no known exploits in the wild at the time of reporting. No specific affected versions or extensions are listed, and technical details are limited, indicating a general awareness of the threat actor's activity rather than a detailed technical breakdown. The lack of CVSS score and limited technical data suggest this is an early or low-severity observation rather than a critical vulnerability or active exploit campaign.

For European organizations, the hijacking of Chrome extensions poses risks primarily related to confidentiality and integrity. Compromised extensions can lead to unauthorized data access, including sensitive corporate information, credentials, or browsing activity. This can facilitate espionage, data leakage, or further compromise of internal systems. Although the severity is rated low, organizations with employees who rely heavily on browser extensions for productivity or security (such as password managers or VPN extensions) could face increased risk if such extensions are hijacked. The impact is more pronounced in sectors with high regulatory requirements for data protection, such as finance, healthcare, and government institutions. Additionally, the widespread use of Chrome in Europe means that even low-severity threats can have broad reach. However, since no active exploits were reported and no specific extensions were identified, the immediate risk is limited but warrants vigilance.

To mitigate the risk of Chrome extension hijacking, European organizations should implement several targeted measures beyond generic advice: 1) Enforce strict policies on the use of browser extensions, allowing only vetted and necessary extensions approved by IT security teams. 2) Regularly audit installed extensions for unusual behavior or unauthorized updates. 3) Educate users about the risks of installing untrusted extensions and the importance of verifying extension sources. 4) Encourage or enforce the use of enterprise-managed browser configurations that restrict extension installation and updates to controlled channels. 5) Monitor threat intelligence feeds for updates on hijacked extensions and promptly remove or update affected extensions. 6) For organizations developing their own extensions, secure developer accounts with multi-factor authentication and monitor for unauthorized access. 7) Collaborate with browser vendors and extension developers to report suspicious activity and receive timely patches or updates.