They should manage extensions like third-party software with identity reach, not like harmless productivity add-ons. That means approving what can be installed, tracking ownership changes, and reviewing whether an extension can read or modify authenticated web sessions. If an extension touches identity flows, it belongs in governance and monitoring scope.
Why This Matters for Security Teams
Browser extensions are not just user convenience tools when they can read pages, inject scripts, or interact with authenticated tabs. Once an extension can observe identity workflows, it can capture session tokens, alter approval steps, or redirect users during login and consent flows. That places it much closer to the risk profile described in the OWASP Non-Human Identity Top 10 than to ordinary endpoint software.
NHI Management Group’s Ultimate Guide to NHIs notes that 92% of organisations expose NHIs to third parties, and browser extensions can become a quiet third-party path into the same identity plane. If an extension is allowed to touch browser-based SSO, admin portals, or password reset flows, it effectively inherits identity reach without the controls usually attached to service accounts or API clients. In practice, many security teams encounter extension abuse only after session theft or consent manipulation has already occurred, rather than through intentional review.
How It Works in Practice
The practical response is to treat extensions as governed software with identity access, not as harmless add-ons. Start by inventorying every approved extension, mapping its publisher, update channel, data permissions, and whether it can run on identity-related domains. Then classify extensions by the workflows they can influence: read-only visibility, session observation, form interaction, or direct modification of authenticated actions.
Where an extension can access identity workflows, current guidance suggests folding it into the same control stack used for other non-human identities: approval, ownership, lifecycle review, logging, and revocation. That includes limiting installation to trusted sources, requiring business justification, and removing stale or orphaned extensions when the owner changes. The Top 10 NHI Issues discussion is a useful reminder that visibility and offboarding gaps are where identity risk usually grows.
- Restrict installation through browser management policies and allowlists.
- Review extension permissions against the specific identity systems they can reach.
- Track ownership, publisher trust, and update behavior over time.
- Monitor for changes in injected scripts, new permissions, or silent capability expansion.
- Revoke access quickly when an extension is deprecated, sold, or no longer needed.
This pairs well with the OWASP Non-Human Identity Top 10 view that identity-relevant software should be governed by reach and privilege, not by whether it is human-operated. These controls tend to break down in unmanaged BYOD environments because the browser itself becomes a shadow deployment surface with inconsistent policy enforcement.
Common Variations and Edge Cases
Tighter extension control often increases user support overhead, requiring organisations to balance identity protection against workflow friction. That tradeoff is especially visible in enterprises that rely on browser-based SSO, developer tooling, or self-service admin portals, where a broad blocklist can break legitimate work.
There is no universal standard for this yet, but best practice is evolving toward risk-based categorisation. A low-risk extension that only changes page appearance should not be treated the same as one that reads DOM content on login pages or can manipulate cookies, redirects, or autofill. Extensions installed by security teams for observability or password handling deserve the same scrutiny as any other privileged third party. The 52 NHI Breaches Analysis shows how often identity compromise follows overlooked trust boundaries, and browser extensions are a modern version of that pattern.
Shared browsers, contractor laptops, and unmanaged personal devices are the hardest cases because policy, telemetry, and revocation are inconsistent. In those environments, the safest answer is to limit identity-touching extensions to managed endpoints and to treat any exception as a monitored risk acceptance, not a routine productivity choice.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and CSA MAESTRO address the attack and risk surface, while NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-03 | Extension access to identity flows creates third-party NHI risk. |
| CSA MAESTRO | GOV-02 | Governance is needed when software can alter authenticated work. |
| NIST AI RMF | AI RMF governance principles fit identity-touching browser automation. |
Classify extensions by identity reach and enforce ownership, approval, and lifecycle controls.
