Annex A 8.5: Secure Authentication

Annex a 8.5: secure authentication requirement expects you to design, implement, and prove secure authentication across systems in scope, with controls that prevent unauthorized access and reduce credential abuse. To operationalize it fast, standardize authentication methods (MFA, SSO, strong credential handling), harden admin access, and retain recurring evidence that the controls run as designed. ^{1 2}

Key takeaways:

• Scope authentication first: user types, systems, privileged paths, and third-party access points.
• Implement a small set of enforceable standards: MFA/SSO, credential rules, and secure admin authentication.
• Evidence wins audits: keep policy, technical configurations, and recurring access/auth logs.

Annex A 8.5 sits in ISO/IEC 27001:2022 as an implementation expectation focused on secure authentication. In practice, auditors treat it as a control that must be consistently enforced across your environment, not a one-off policy statement. You need a clear authentication standard, technical enforcement in your identity stack, and proof that the standard is applied to the systems and users in scope for your ISMS. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path is to translate “secure authentication” into a small number of enforceable requirements that engineering and IT can implement without ambiguity: (1) how users authenticate (SSO where possible), (2) when MFA is mandatory, (3) how credentials are created, stored, rotated, and revoked, and (4) how you handle privileged/admin access and machine-to-machine authentication. Then you build an evidence cadence that demonstrates operation over time, not just point-in-time screenshots. ²

This page is requirement-level guidance to help you operationalize Annex a 8.5: secure authentication requirement quickly, with steps, artifacts, audit questions, and a practical execution plan.

Regulatory text

Provided excerpt (summary form): “ISO/IEC 27001:2022 Annex A control 8.5 implementation expectation (Secure Authentication).” ^{1 2}

What the operator must do

You must define and implement secure authentication controls for access to systems and services in the ISMS scope, then maintain evidence that those controls are consistently applied. Auditors typically expect:

• Documented authentication rules (who must use what method, where, and under which conditions).
• Technical enforcement (identity provider settings, MFA policies, privileged access controls).
• Operational processes (joiner/mover/leaver, access reviews, exception handling).
• Logs and monitoring that show authentication is working and issues are handled.

Because ISO control text is licensed, the excerpt above is intentionally high-level. Your job is to translate it into specific, testable requirements your teams can implement and you can evidence. ¹

Plain-English interpretation (what Annex A 8.5 is asking for)

Secure authentication means: only legitimate users and approved non-human identities can access your systems, using authentication methods that resist common attacks (credential stuffing, phishing, brute force, session hijacking, and unauthorized admin access). You also need to reduce blast radius when credentials fail: strong MFA, tight privileged access, and rapid revocation.

A practical way to frame Annex a 8.5: secure authentication requirement is to answer four questions in a standard:

1. What identities exist? Workforce users, contractors, third parties, customers, service accounts, API clients.
2. How do they authenticate? SSO, MFA, SSH keys, certificates, tokens, passkeys.
3. Where is it enforced? Cloud console, VPN, SaaS apps, admin panels, production access, CI/CD, databases.
4. How do you prove it? Config exports, policy objects, access logs, and review records.

Who it applies to (entity and operational context)

Applies to: Service organizations implementing ISO/IEC 27001:2022 controls in an ISMS, including organizations delivering SaaS, managed services, professional services with system access, and hybrid environments. ¹

Operationally applies to:

• Workforce identities: employees, interns, contractors, temps.
• Privileged identities: admins, cloud console superusers, database admins, break-glass accounts.
• Third-party access: support partners, MSPs, auditors, implementation consultants, and any external entity with credentials or federation.
• Customer authentication (if in scope): SSO/SAML/OIDC settings, MFA options, password policies, session controls.
• Non-human identities: service accounts, API keys, robots, CI/CD runners, secrets used in automation.

If your scope excludes certain systems, you still need to show the boundary is real (network segmentation, separate identity tenants, or formal scope statements). Otherwise auditors will sample broadly.

What you actually need to do (step-by-step)

Step 1: Define an “Authentication Standard” that engineers can enforce

Create a short standard (two to four pages) that includes:

• Approved authentication methods by user type (workforce, admin, customer, third party).
• MFA requirements by risk tier (at minimum: privileged access and remote access paths).
• Password/secret rules (length/complexity guidance, storage, reset flows, lockout).
• Session controls (idle timeout, re-authentication for sensitive actions, device trust if used).
• Non-human authentication (API keys, OAuth clients, certificates) with issuance and rotation rules.
• Exception process (who can approve, compensating controls, expiry dates, review cadence).

Keep it testable. Every statement should map to a configuration or log you can show.

Step 2: Build an authentication inventory and scope map

Produce an inventory that lists, for each in-scope system:

• System name and owner
• User populations (workforce, third party, customers)
• Authentication method (SSO local login, federated SSO, etc.)
• MFA enforced (yes/no and where enforced)
• Privileged/admin entry points (URLs, consoles, bastions)
• Log source (where auth logs land)

This becomes your audit sampling backbone.

Step 3: Centralize identity where feasible (IdP-first)

Most teams operationalize Annex A 8.5 by making the Identity Provider (IdP) the enforcement point:

• Enforce MFA at the IdP for workforce and admins.
• Prefer SSO over local accounts in SaaS.
• Restrict legacy auth (basic auth, app passwords) unless there is a documented exception.

If you cannot centralize a system, treat it as a “local auth exception” and require stronger compensating controls (stricter MFA at the app, stronger monitoring, and shorter credential lifetimes).

Step 4: Harden privileged authentication (the auditor’s favorite sample)

Implement and document:

• Separate admin roles and least privilege.
• MFA required for admin consoles and privileged actions.
• Break-glass accounts with strong controls (stored securely, access logged, periodic checks).
• No shared admin accounts unless formally approved with compensating controls (shared accounts are hard to defend in audits because attribution breaks).

Tie privileged access to a ticketing or approval workflow when feasible, so you can evidence business justification.

Step 5: Control credential lifecycle (joiner/mover/leaver + reset)

Operationalize identity lifecycle:

• Provisioning: identity proofing steps, role assignment, group-based access.
• Changes: role changes trigger access updates.
• Deprovisioning: disable and remove access promptly when a user leaves or a third party engagement ends.
• Resets: verify identity before password resets; protect helpdesk processes; log resets.

For third parties, require named accounts, defined expiry dates, and periodic confirmation that access is still needed.

Step 6: Manage non-human authentication like production infrastructure

For service accounts and API credentials:

• Issue through an owner and purpose statement.
• Store in a secrets manager or equivalent controlled store.
• Rotate and revoke on staff changes and compromise events.
• Block hard-coded secrets in code repositories through scanning and reviews (and document the control even if tooling is separate).

Auditors commonly ask how you prevent “orphaned” keys and service accounts.

Step 7: Instrument evidence capture (recurring, not manual heroics)

Map Annex A 8.5 to recurring evidence:

• Monthly or quarterly exports of IdP MFA policy settings.
• Screenshots or config exports for key apps that cannot use SSO.
• Samples of authentication logs (successful and failed), and alerts for suspicious patterns.
• Records of exceptions with approvals and expirations.

Daydream (or any GRC system you use) fits here as the control-to-evidence layer: assign owners, define the evidence cadence, and keep the artifacts in one place so audits are retrieval, not archaeology.

Required evidence and artifacts to retain

Use this as an auditor-ready checklist.

Evidence artifact	What it proves	Owner
Authentication Standard (policy/standard)	Defined requirements for secure authentication	GRC + Security
System authentication inventory	Scope coverage and where enforcement occurs	IT/Security Architecture
IdP configuration exports (MFA, conditional access)	Technical enforcement of MFA and access rules	IAM team
Privileged access design (roles, admin groups)	Least privilege and hardened admin auth	Security/Cloud Admin
Break-glass procedure + access logs	Controlled emergency access	Security Ops
Joiner/mover/leaver procedure + tickets	Credential lifecycle and timely revocation	IT + HR
Third-party access register (named accounts, expiry)	External access governance	Vendor/TPRM + IT
Exception register (approvals, compensating controls, expiry)	Controlled deviations	GRC
Authentication log retention + samples	Operation and monitoring	SecOps

Common exam/audit questions and hangups

Expect auditors to test design and operation. Common questions:

• “Show me where MFA is enforced for administrators and remote access.”
• “Which applications still have local logins, and what compensating controls exist?”
• “How do you onboard and offboard third-party users? Show recent examples.”
• “How do you manage service accounts and API keys? Who owns them?”
• “Where do authentication logs go, and how do you review or alert on anomalies?”
• “Show me your exception process. Are exceptions time-bound and reviewed?”

Hangups that slow audits:

• You have a policy, but no system-level mapping.
• MFA exists, but privileged paths have carve-outs.
• Third parties authenticate outside your IdP with shared accounts.
• Non-human identities are unmanaged and unowned.

Frequent implementation mistakes (and how to avoid them)

1. Mistake: Treating MFA as “enabled somewhere” rather than enforced everywhere it matters.
   Fix: document the required coverage (admins, remote access, key systems) and pull evidence from the enforcement point (IdP or app policy).

2. Mistake: Ignoring third-party authentication because “they’re not employees.”
   Fix: require named accounts, time-bound access, and the same baseline authentication controls for third-party interactive access.

3. Mistake: Forgetting service accounts and API keys.
   Fix: maintain a register with owners, purposes, and rotation/revocation steps. Audit samples will include automation identities.

4. Mistake: No exception expiry dates.
   Fix: every exception needs an owner, compensating controls, and a clear end date. Treat “temporary” as a measurable attribute.

5. Mistake: Evidence is screenshots taken the week before the audit.
   Fix: establish recurring evidence capture so you can show operation over time (config snapshots, access review records, and log samples).

Enforcement context and risk implications

ISO 27001 is a certifiable standard, not a regulator, so “enforcement” usually shows up as audit nonconformities, certification delays, surveillance audit findings, and customer trust impacts. Weak authentication is also a common root cause in security incidents because credential theft turns into account takeover, privilege escalation, and lateral movement. Annex a 8.5: secure authentication requirement is one of the controls customers expect to be mature, because it touches every system boundary.

Practical 30/60/90-day execution plan

First 30 days (stabilize and define)

• Publish the Authentication Standard with clear MFA and privileged access rules.
• Build the in-scope authentication inventory (start with highest-risk systems and admin consoles).
• Stand up an exception register with approval workflow and expiry requirement.
• Identify top gaps: apps without SSO, admin paths without MFA, unmanaged service accounts.

Days 31–60 (enforce and evidence)

• Enforce MFA via IdP conditional access for workforce and administrators.
• Remove or restrict legacy authentication methods where possible.
• Implement third-party access governance: named accounts, expiry, and owner sign-off.
• Start recurring evidence capture: IdP policy export, exception register snapshot, sample auth logs.

Days 61–90 (operational maturity)

• Formalize non-human identity management: service account register, secrets handling, rotation/revocation steps.
• Add monitoring: alerting on suspicious auth patterns and admin logins.
• Run an internal control test: pick sample systems and prove authentication controls end-to-end with retained artifacts.
• Prepare audit-ready packets per system: auth method, MFA enforcement proof, logs, and exceptions.

Daydream can reduce cycle time here by mapping Annex A 8.5 to owners, systems, and recurring evidence tasks so you do not rebuild audit narratives each quarter.

Frequently Asked Questions

Does Annex A 8.5 require MFA everywhere?

The control expects “secure authentication,” which auditors commonly test through MFA enforcement in high-risk contexts like privileged access and remote access. Define where MFA is mandatory in your standard and prove enforcement through IdP or application configuration. ²

How do we handle legacy systems that cannot support SSO or MFA?

Treat them as documented exceptions with compensating controls (tighter network access, stronger monitoring, restricted accounts) and a plan to remediate. Keep an exception record with an owner and expiry so it remains controlled.

Are service accounts and API keys part of secure authentication?

Yes if they provide access to in-scope systems or data. Maintain ownership, issuance controls, secure storage, and revocation/rotation procedures, then retain evidence that these steps occur.

What evidence is most persuasive in an ISO 27001 audit for secure authentication?

Auditors respond well to objective configuration evidence (IdP policy exports, admin role settings) plus operational records (access tickets, termination samples, exception approvals). Add authentication log samples that show the control operates beyond policy.

How should third-party users authenticate?

Prefer federated SSO to your IdP or controlled named accounts with MFA and time-bound access. Avoid shared credentials because they weaken accountability and complicate investigations.

How do we “map” Annex A 8.5 to operations without creating paperwork overhead?

Map the control to a small set of enforceable technical statements (IdP MFA rules, privileged access rules, credential lifecycle) and automate recurring evidence capture. A GRC workflow tool such as Daydream helps by assigning owners and storing evidence on a cadence.

Footnotes

1. ISO/IEC 27001 overview

2. ISMS.online Annex A control index