Why do browser extensions create identity and access risk beyond normal endpoint software?

Browser extensions sit inside the user’s active session, so they can see behaviour, collect telemetry, and influence requests in a context that already has trust. That makes them identity-adjacent footholds rather than simple utilities. The risk grows when extensions can update themselves or fetch remote instructions after installation.

Why This Matters for Security Teams

Browser extensions are not just endpoint software with a smaller install footprint. They run inside the user’s authenticated browser session, which means they can observe page content, modify requests, and interact with tokens or cookies that already carry trust. That creates an identity and access problem, not just a software hygiene problem. Guidance in the OWASP Non-Human Identity Top 10 and the NIST Cybersecurity Framework 2.0 both point toward controlling trusted software behaviour, but extensions sit in a particularly exposed layer because they inherit the user’s context.

The risk is amplified when an extension can update itself, request new permissions, or pull remote code or configuration after installation. In practice, that makes the extension an identity-adjacent foothold that can be repurposed without a traditional malware event. The 2024 The 2024 ESG Report: Managing Non-Human Identities found that 72% of organisations have experienced or suspect a non-human identity breach, which is a useful reminder that identity abuse often starts in trusted automation rather than obvious intrusion. In practice, many security teams encounter extension abuse only after session misuse or token theft has already occurred, rather than through intentional review.

How It Works in Practice

Extensions create risk because they operate with a blend of user-level trust and programmatic reach. A benign extension may only decorate pages, but a risky one can read page content, watch form input, intercept network activity, inject scripts, and call external services. If the extension’s permissions include broad host access or message passing to background processes, the trust boundary becomes much wider than most endpoint software reviews assume.

The practical control problem is to treat extensions as privileged software components with identity-like behaviour. Current best practice is evolving, but a strong baseline includes inventory, permission minimisation, publisher review, update governance, and runtime monitoring for unexpected network destinations. Security teams should also check whether the extension is linked to a service identity, API token, or remote instructions that can change its behaviour after deployment. The Ultimate Guide to NHIs shows why that matters: secrets and identities often outlive their intended use, and browser extensions can become a delivery path for the same kind of stale trust. For implementation detail, the OWASP Non-Human Identity Top 10 is helpful for mapping identity exposure to the behaviours that actually need control.

• Review extension permissions against actual business need, not the vendor’s default install prompt.
• Restrict installation to allowlisted extensions and approved publishers.
• Monitor for remote configuration, self-update channels, and unusual egress.
• Treat token access, session access, and background messaging as identity controls, not just app features.

These controls tend to break down in environments with unmanaged browsers, rapid self-service installs, or extensions that rely on dynamic remote code because the approved behaviour can change after security review.

Common Variations and Edge Cases

Tighter extension control often increases user friction and support overhead, so organisations need to balance productivity against session protection. That tradeoff is real, especially where teams depend on productivity extensions, password tools, or customer-support plugins that legitimately interact with authenticated content.

There is no universal standard for this yet, but current guidance suggests treating the highest-risk cases differently: extensions with broad site access, access to messaging APIs, or the ability to load remote content should be reviewed more like privileged tooling than ordinary desktop apps. Browser-managed extension policies can reduce exposure, but they do not eliminate risk if a sanctioned extension later changes its permission set or fetches new logic. The NHI problem becomes more visible when an extension behaves like a persistent agent inside the session, which is why NHI governance and browser control increasingly overlap. NIST’s framework language is useful here because it encourages continuous risk management rather than one-time approval, and Top 10 NHI Issues is a practical reminder that over-privilege and weak lifecycle control are recurring failure modes, not edge cases.

Extensions also become harder to assess when they are tied to SSO flows, clipboard access, or enterprise automation. In those cases, the question is not whether the software is “malicious” in a binary sense, but whether it can be repurposed to act outside its intended identity boundaries.

Related resources from NHI Mgmt Group

• Why do browser extensions and SaaS sessions create identity risk?
• Why do browser attacks create identity risk instead of just web risk?
• Why do browser-based attacks create extra risk for NHI and human identity programmes?
• Why do web server vulnerabilities create identity and access risk for NHI programmes?