Strictly necessary cookies support core website functions such as login, form submission, and preference handling. Performance cookies measure visits, traffic sources, and page popularity so teams can improve the site. The first category is usually exempt from consent because the site cannot function properly without it, while the second should be optional and clearly disclosed to the user.
Why This Matters for Security Teams
Consent programmes fail when teams blur the line between functionality and measurement. Strictly necessary cookies are tied to core site behaviour, while performance cookies feed analytics and optimisation. That distinction matters because a consent banner is not just a UX control, it is a legal and trust boundary. The EU General Data Protection Regulation (GDPR) expects a defensible basis for processing, and that basis changes depending on whether the cookie is essential or optional.
Practitioners also need to account for how vendors classify cookies in practice. A cookie used for authentication, load balancing, or preserving a user’s form state may be strictly necessary, but a cookie that tracks visits, referrers, or page popularity is typically performance-related and should remain opt-in. NHIMG’s Ultimate Guide to NHIs â What are Non-Human Identities is useful here because it reinforces a broader governance pattern: anything that persists or acts on behalf of a system should be classified by function, not by how convenient it is to enable. In practice, many security teams encounter misclassification only after a complaint, audit finding, or tag-manager change has already exposed the site.
How It Works in Practice
The operational test is simple: ask whether the cookie is strictly required to deliver the service the user explicitly requested. If the answer is yes, it is usually treated as strictly necessary. If the cookie exists to observe behaviour, measure traffic, or improve site performance, it generally belongs in the consented category. Current guidance suggests documenting that decision at the cookie name or purpose level, not just at the vendor level, because one third-party script can set multiple cookies with different purposes.
In a mature consent programme, teams map each cookie to a lawful purpose, a data owner, and a retention period. That inventory should be reviewed whenever a tag, CDN, analytics package, or authentication flow changes. The Ultimate Guide to NHIs â What are Non-Human Identities is a good reminder that identity and access controls rely on clear lifecycle management; the same discipline applies to browser-side data collection.
- Classify cookies by purpose, not by marketing label.
- Allow strictly necessary cookies only when they are essential to login, session continuity, security, or user-requested functionality.
- Block performance cookies until the user opts in, then record the consent decision.
- Re-test after releases, because scripts often change behaviour without notice.
- Ensure the disclosure matches actual behaviour, including third-party analytics and telemetry.
Teams often pair this with a privacy review of the consent banner itself, because a banner that nudges users to accept optional cookies without a genuine choice can undermine the programme even when the technical classification is correct. These controls tend to break down when tag managers let marketing scripts load before consent decisions are enforced.
Common Variations and Edge Cases
Tighter cookie classification often increases operational overhead, requiring organisations to balance privacy confidence against analytics continuity. Some cookies sit in a grey area, especially when they support security, fraud detection, load balancing, or A/B testing. Best practice is evolving, and there is no universal standard for every scenario, so teams should document the rationale for each borderline case rather than assume a one-size-fits-all answer.
One common edge case is when a cookie serves both a necessary and a measurement function. If it is technically indispensable for service delivery, it may qualify as strictly necessary, but any additional telemetry should be separated and treated as optional where feasible. Another edge case is first-party analytics that is aggregated and privacy-preserving; even then, the consent decision depends on jurisdiction and implementation details. For policy interpretation, teams should align legal review with the consent platform configuration, because a policy that is correct on paper can still fail if the banner, script loader, and tag manager are not synchronized.
For practical governance, treat classification as a living inventory, not a one-time legal check. That approach mirrors the discipline described in NHIMG’s Ultimate Guide to NHIs â What are Non-Human Identities: identify what a component does, constrain its scope, and review it when the environment changes.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST CSF 2.0, NIST AI RMF and NIST SP 800-63 set the technical controls, while EU AI Act define the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | GV.RM-02 | Cookie classification needs risk-informed governance and documented decisions. |
| NIST AI RMF | Consent programmes need policy and accountability across data collection choices. | |
| NIST SP 800-63 | §5.2 | Strictly necessary cookies often support authenticated sessions and user continuity. |
| EU AI Act | Not directly applicable, but governance logic for disclosure and user choice is analogous. |
Treat session cookies as essential only when they are required for the requested authenticated service.
Related resources from NHI Mgmt Group
- What is the difference between attack surface management and NHI governance?
- What is the difference between reviewing human access and reviewing NHIs?
- What is the difference between role-based access and API key governance for NHI security?
- What is the difference between human IAM controls and NHI governance?
