Browser extensions are powerful, but without proper oversight, they become a silent threat. Left unmanaged, they can be exploited to access sensitive data, hijack user sessions, or serve as gateways for future attacks. Here are the top five reasons why extension management must be a priority for every security team:

1. Sensitive Data Loss and Credential Theft

Malicious or over-permissive extensions can read clipboard contents, intercept form data, or exfiltrate sensitive business information, such as credentials, financial records, or customer data. This can lead to unauthorized access, regulatory violations, and serious financial consequences.

2. Reconnaissance for Future Attacks

Extensions can silently monitor browser activity, gathering reconnaissance data like login portals, internal tools, and SaaS URLs. Threat actors use this insight to craft highly targeted phishing campaigns or exploit vulnerabilities aligned with your organization’s specific workflows.

3. User Manipulation and Redirects

Compromised or malicious extensions can alter the browser experience by injecting misleading ads, fake system messages, or redirecting users to phishing sites. These tactics increase the likelihood of credential theft, PUP (potentially unwanted program) installation, or full malware infection. A specific malware campaign led to over 300,000 browsers and devices infected by a browser add-on that performs remote code execution (RCE), collects data on the user, and redirects traffic.

4. Shadow IT and Vulnerability Risk

Unmanaged or outdated extensions introduce blind spots into your security posture. Without visibility or version control, security teams can’t assess which extensions pose a risk or prevent employees from installing vulnerable or unauthorized tools.

5. Risks from Third-Party Compromise

Even trusted browser extensions can become attack vectors. If a developer’s account or publishing infrastructure is compromised, threat actors can deliver malicious updates through legitimate channels, transforming a commonly used tool into a stealthy threat within your environment. A real-world example occurred when Cyberhaven was breached via a compromised Chrome Web Store admin account, allowing attackers to publish a malicious extension under the company’s name.

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Proper extension management isn’t just about control but about proactive risk reduction. The more visibility you have into what’s running in your users’ browsers, the faster you can identify threats and enforce smarter, safer policies.

For a deeper dive into managing browser extension risks, download our full guide.