Browser Extension Threats: Persistent Access and Data Theft, MITRE ID: T1176

Abstract: Adversaries may exploit Internet browser extensions to establish persistent access to victim systems, steal sensitive data, and facilitate the installation of additional malware. Malicious extensions can be installed through malicious app store downloads, social engineering, or by adversaries that have already compromised a system. The extensions have access and permissions to everything that the browser can access, which can include browsing history, login credentials, and more. These extensions can silently browse websites in the background, steal all information entered into the browser, and be used as an installer for a remote access Trojan (RAT) for persistence. Detection and prevention of these attacks can be challenging due to the varying levels of security and limited security measures on browser app stores.

Introduction: Browser extensions or plugins are small programs that can add functionality and customize aspects of Internet browsers. They can be installed directly or through a browser’s app store, and generally have access and permissions to everything that the browser can access. This can include browsing history, login credentials, and other sensitive data. Malicious extensions can be used to steal this sensitive data, establish persistent access, and facilitate the installation of additional malware.

Detection: Detection of malicious browser extensions can be challenging due to the varying levels of security and limited security measures on browser app stores. However, there are some strategies that can be employed to detect these threats.

1. Regularly review the extensions installed in browsers: IT administrators and users should regularly review the extensions installed in browsers to identify any new or unknown extensions that have been installed. This can be done by navigating to the browser’s extension manager and reviewing the list of installed extensions.
2. Monitor browser network activity: Adversaries may use browser extensions to communicate with command and control servers or to exfiltrate data. Monitoring browser network activity can help detect such activities.
3. Monitor system logs: System logs can provide information on any changes to the system or browser, including the installation of new extensions. IT administrators should regularly review system logs for suspicious activities.
4. Use security solutions: Deploying security solutions such as endpoint detection and response (EDR) or network traffic analysis (NTA) can help detect malicious browser extensions.

Prevention: Prevention is key to stopping these types of attacks from happening. Here are some prevention strategies:

1. Educate users: Users should be educated on safe browsing practices and should avoid installing extensions from untrusted sources.
2. Use browser security features: Browsers have built-in security features such as sandboxing and permissions that can be used to restrict extension access to sensitive data.
3. Use app store security features: Browser app stores have security features such as reviews, ratings, and user feedback that can be used to identify potentially malicious extensions.
4. Use security solutions: Security solutions such as web content filtering, firewalls, and antivirus software can help prevent the installation of malicious browser extensions.

Conclusion: Browser extension threats are a serious issue that can result in data theft, persistent access, and installation of additional malware. Detection and prevention of these threats can be challenging, but by implementing the strategies outlined in this white paper, organizations can reduce the risk of falling victim to these types of attacks.