ISO 27001 Annex A 5.17 Authentication Information Explained

ISO 27001 Authentication Information

ISO 27001 Annex A 5.17 Authentication Information is an ISO 27001 control that requires an organisation to mange the full life cycle of authentication information.

Authentication information is about providing a way for people to prove they are who they say there when accessing systems or information.

Authentication information is the information that is used to gain access to systems and resources.

Key Takeaways

ISO 27001 Annex A 5.17 requires organisations to control the allocation and management of authentication information (passwords, PINs, biometrics, or tokens) through a formal management process. This control ensures that the “secrets” used to prove an identity remain confidential and are handled securely throughout their entire lifecycle. The goal is to prevent unauthorised access by ensuring that authentication data is never shared, easily guessed, or left in clear text.

Purpose

The purpose of ISO 27001 Annex A 5.17 is a preventive control that ensures proper entity authentication and prevents failures of authentication processes.

Definition

The ISO 27001 standard defines ISO 27001 Annex A 5.17 as:

Allocation and management of authentication information should be controlled by a management process, including advising personnel on the appropriate handling of authentication information.

ISO 27001:2022 Annex A 5.17 Authentication Information

Explanation

ISO 27001 Annex A 5.17 Authentication Information is a security control that establishes a formal management process for allocating and protecting credentials like passwords and biometrics. Implementing this control ensures confidentiality of secrets, providing a significant business benefit by preventing unauthorised access and mitigating credential-based breaches.

Requirement

• Secure Allocation: You must have a process for creating and distributing initial credentials. Temporary passwords should be unique, complex, and forced to change upon first login.
• Identity Verification: Before issuing new or replacement credentials (e.g., a password reset), you must verify the identity of the requester to prevent social engineering attacks.
• Password Management Systems: Organizations should use systems that enforce strong password criteria (length and complexity) and protect stored credentials using industry-standard encryption.
• User Awareness: Personnel must be briefed on their responsibilities, such as not sharing passwords, avoiding reuse across different sites, and using a vetted Password Manager.
• MFA Implementation: While not explicitly mandated by the text of A.5.17, the 2022 standard strongly implies the use of Multi-Factor Authentication (MFA) for sensitive or remote access as a best-practice management process.
• Change Mandatory Defaults: Any default manufacturer passwords or PINs must be changed immediately upon system installation.

Audit Focus

1. Reset Procedures: “If I call your IT helpdesk and say I’ve forgotten my password, how do they verify it’s really me before resetting it?”
2. MFA Everywhere: “Show me your login screen for your email and VPN. Do they require MFA? If not, how do you justify the risk of using only single-factor authentication?”
3. Password Hygiene: They may perform “desk checks” to look for written passwords (post-it notes) or ask employees how they generate and store their secrets.

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Allocating the authentication information

When it comes to creating the passwords and pins that will be used you may want to consider generating them automatically. This can make the process more efficient. To consider is

1. Creating temporary authentication information for first time use
2. Making sure the temporary authentication is hard to guess and unique for each person
3. That it must be changed on first use.

We do not want to give access to any old Tom, Dick or Harry so you will have a way to check and verify the identity of any person making the request and any person being given new, updated or replacement credentials. They may, or may not, be the same person.

When we send authentication information to people we are going to do it in a secure way. We are not going to email it or send it in clear text where possible.

The standard wants a step where the user acknowledges that they have received this information.

We keep a record of what we have allocated and what we have managed and we protect that record.

Lastly if a vendor or supplier provides for default passwords, pins and authentication information we change that immediately.

What the user is responsible for

Users do have some responsibility. They are not to share their passwords or secret authentication information.

If there is a compromise or a leak then the information and credentials are change immediately that you are notified.

Strong passwords, where passwords are used are implemented. This means passwords should not be easy to guess, or be based on something someone could guess or find out. The example is not to use dictionary words or combinations of. This is actually bullshit as the use of dictionary words to make up a phrase would be an ideal password but the standard thinks it knows better.

Passwords have a minimum length according to the standard which is pure genius as any word has a minimum length. It gives no guidance so choose wisely.

Ideally we do not reuse password across different systems.

Contracts of employment include the obligation to follow these rules.

Guidance on a password management system

General guidance on password management systems, which ever you choose, would be

• Users are allowed to select and change their own passwords
• They enforce strong passwords according to best practice
• They force users to change passwords at first use
• They force password changes as required such as after a security incident
• Ideally they prevent re-use of previous passwords
• They prevent the use of common passwords
• Where possible they take account of compromised accounts and passwords and prevent their use
• They do not display passwords on the screen when being entered
• They do not store or send passwords in clear text
• Passwords should be encrypted

Exceptions

There are many ways in which the standard is still old fashioned and a little out of date. You see this come up a lot where it tells you what to do and then says, but in the real world we know you cannot, so do not.

Some exceptions would be that clearly, other ways to authenticate other than passwords are acceptable. Consider tokens, card, biometrics.

Contrary to the standard there is an argument to not frequently change passwords. It does acknowledge this as a scenario which is good. It is about finding the balance for you based on risk and business need and being able to argue that with an auditor.

ISO 27001 Access Control Policy Template

The ISO 27001 Access Control Policy template is pre written and ready to go. It is one of the required ISO 27001 policies that sets out the organisations approach to access control.

How to implement it

Implementing the ISO 27001 Annex A 5.17 control requires a robust approach to managing authentication information. As a Lead Auditor, I recommend following this structured process to ensure that passwords, biometrics, and cryptographic keys are protected throughout their entire lifecycle, from initial allocation to eventual revocation.

1. Formalise the Authentication Information Policy

Establishing a clear set of rules is the foundation of this control. You must document the organisational requirements for the creation, distribution, and protection of authentication information.

• Define minimum password length and complexity requirements.
• Specify the mandatory use of Multi-Factor Authentication (MFA) for all remote and privileged access.
• Document the prohibited practices, such as sharing credentials or storing them in unencrypted plain text files.

2. Update the Asset Register for Authentication Systems

You cannot protect what you have not identified. Ensure your Asset Register includes all systems, applications, and databases that store or process authentication data.

• Identify the owners of each authentication system.
• Classify the sensitivity of the authentication data held within each asset.
• Link these assets to your wider Information Security Management System (ISMS) for risk assessment purposes.

3. Provision Unique User Identifiers

Accountability is a core tenet of ISO 27001. You must ensure that every user is assigned a unique ID to maintain a clear audit trail of actions performed.

• Eliminate the use of shared or generic accounts, such as “admin” or “guest,” wherever technically possible.
• Assign Identity and Access Management (IAM) roles based on the principle of least privilege.
• Ensure that unique IDs are mapped directly to verified individuals.

4. Configure Multi-Factor Authentication (MFA)

Relying solely on passwords is no longer sufficient for modern security. Implementing MFA adds a critical layer of protection against credential theft.

• Deploy MFA for all cloud-based services and internal systems containing sensitive data.
• Utilise hardware tokens, biometrics, or authenticator apps rather than less secure SMS-based codes.
• Ensure the MFA solution is integrated into the central identity provider.

5. Enforce Technical Password Constraints

Use technical controls to enforce the policy requirements established in step one. This reduces the reliance on human diligence for security.

• Implement system settings that prevent the reuse of previous passwords.
• Enforce account lockout thresholds to mitigate the risk of brute-force or dictionary attacks.
• Enable “masking” of authentication information during entry to prevent shoulder surfing.

6. Secure Authentication Information Storage

The storage of authentication data must be resilient against unauthorised access or data breaches. This involves the use of strong cryptographic techniques.

• Ensure passwords are stored using salted, one-way cryptographic hashes.
• Protect cryptographic keys and biometric templates with encryption at rest.
• Limit administrative access to the underlying databases where authentication data resides.

7. Establish Secure Distribution Channels

The moment of credential issuance is a high-risk period. You must establish secure methods for delivering initial or reset authentication information to users.

• Verify the identity of the recipient before providing new credentials.
• Use secure, out-of-band communication channels for password delivery.
• Force an immediate password change upon the first login after a reset or initial provision.

8. Deliver Information Security Awareness Training

Users are often the weakest link in the authentication chain. Regular training ensures they understand their responsibilities in protecting their credentials.

• Conduct training sessions on how to recognise phishing attempts designed to steal credentials.
• Educate staff on the importance of keeping authentication information confidential.
• Provide guidance on the use of approved corporate password managers.

9. Implement Prompt Revocation Protocols

Authentication information must be managed through the entire employee lifecycle. Failure to revoke access promptly creates significant security gaps.

• Integrate HR termination processes with IT de-provisioning workflows.
• Ensure credentials are revoked or changed immediately upon an employee’s exit or a change in their role.
• Update the Record of Employment (ROE) documents to confirm the return of any physical authentication tokens.

10. Conduct Regular Access Audits

Continuous monitoring and review are essential to maintain the effectiveness of this control. Regular audits help identify orphaned accounts or policy violations.

• Perform quarterly reviews of privileged account access and activity.
• Audit logs for failed login attempts to identify potential brute-force patterns.
• Review the Asset Register and IAM roles to ensure they remain accurate and aligned with current business needs.

User Responsibility Checklist

Rule	Do	Don’t
Storage	Use a Password Manager (e.g., 1Password).	Write it on a Post-It note.
Sharing	Delegate access properly (separate accounts).	Text your password to a colleague.
Complexity	Use Passphrases (e.g., “Correct-Horse-Battery”).	Use “Password123”.
Reuse	Unique password for every site.	Use the same password for Work and Facebook.
MFA	Approve only requests you triggered.	Approve random push notifications.

How to comply

To comply with ISO 27001 Annex A 5.17 you are going to implement the ‘how’ to the ‘what’ the control is expecting. In short measure you are going to

• Implement a process for creating, updating and removing authentication information

How to audit it

As an ISO 27001 Lead Auditor, I have designed this audit process to verify that your organisation is effectively managing and protecting authentication information. Following these steps will ensure that your controls for Annex A 5.17 are not only documented but are technically robust and resistant to unauthorised access.

1. Inspect the Formal Authentication Information Policy

Examine the documented policy to ensure it establishes clear rules for the creation, distribution, and lifecycle management of authentication data.

• Confirm that the policy mandates Multi-Factor Authentication (MFA) for all remote and privileged access.
• Verify that password complexity, rotation requirements, and length are defined in alignment with industry best practices.
• Check that the policy explicitly prohibits the sharing or insecure storage of credentials.

2. Reconcile the Asset Register with Authentication Databases

Validate that all systems, applications, and databases that store or process authentication information are correctly identified and classified.

• Inspect the Asset Register to ensure it includes all Identity and Access Management (IAM) systems.
• Verify that the owners of these authentication assets are clearly assigned and aware of their security responsibilities.
• Cross-reference system logs with the register to identify any undocumented “shadow IT” authentication stores.

3. Evaluate Unique User IDs and IAM Role Assignments

Audit the system configurations to ensure that every individual is assigned a unique identifier to maintain accountability.

• Search for the use of shared or generic accounts, such as “Administrator” or “Support”, and verify if they have been disabled.
• Review IAM roles to confirm that the principle of least privilege is applied to each user identifier.
• Examine the process for verifying an individual’s identity before a unique ID is provisioned.

4. Validate the Enforcement of Multi-Factor Authentication (MFA)

Verify that technical controls are in place to enforce MFA across the organisational perimeter and for sensitive internal systems.

• Sample 10% of user accounts to confirm that MFA is active and cannot be bypassed by the user.
• Ensure that MFA methods used are resilient, such as hardware tokens or authenticator apps, rather than SMS-based codes.
• Test the system response when an MFA prompt is rejected to ensure access is denied immediately.

5. Test Technical Password Complexity and Lockout Constraints

Perform technical testing on system settings to confirm that policy requirements for passwords are being enforced automatically.

• Attempt to set a password that falls below the minimum complexity or length requirements to test system rejection.
• Verify that account lockout thresholds are active after a specified number of failed login attempts.
• Confirm that the system forces a password change upon initial login for all new or reset accounts.

6. Audit the Secure Storage and Hashing of Credentials

Examine the technical methods used to store authentication information to ensure it is protected from data breaches or unauthorised viewing.

• Review database configurations to confirm that passwords are stored using salted, one-way cryptographic hashes.
• Verify that biometric templates and cryptographic keys are encrypted at rest using industry-standard algorithms.
• Confirm that authentication information is masked during entry to prevent shoulder-surfing risks.

7. Verify Secure Delivery and Identity Verification Protocols

Inspect the process for distributing initial or reset authentication information to ensure it remains confidential during transit.

• Observe the service desk process for credential resets to ensure identity is verified before information is released.
• Verify that secure, out-of-band communication channels are used for the distribution of temporary credentials.
• Check that temporary credentials have a short expiration window and are invalidated after their first use.

8. Review Security Awareness Training Completion Rates

Examine training logs to ensure that all personnel understand their responsibilities regarding the protection of authentication information.

• Inspect the training materials to confirm they cover password hygiene, MFA usage, and phishing recognition.
• Verify that 100% of staff have completed the mandatory security awareness programme within the last 12 months.
• Review records of targeted training provided to privileged users who manage authentication systems.

9. Confirm Immediate Revocation via Record of Employment (ROE) Logs

Audit the offboarding process to ensure that authentication information is revoked immediately when an individual leaves the organisation.

• Sample the last five employee exits and compare their departure date with the timestamp of their account deactivation.
• Review Record of Employment (ROE) documents to ensure physical authentication tokens have been returned and decommissioned.
• Verify that access is revoked or modified immediately upon a change in job role or responsibilities.

10. Examine Periodic Access Review and Log Monitoring Reports

Analyse the output of regular monitoring activities to ensure the continued effectiveness of authentication controls.

• Review the reports from the last quarterly access review to ensure that “orphaned” accounts were identified and removed.
• Inspect system logs for evidence of monitoring for brute-force attacks or suspicious login patterns.
• Confirm that any identified security incidents related to authentication were managed according to the formal incident response plan.

How to pass the audit

To pass an audit of ISO 27001 Annex A 5.17 you are going to make sure that you have followed the steps above in how to comply.

What the auditor will check

The audit is going to check a number of areas. Lets go through the most common

1. That you have not done something stupid

The auditor is going to check the rules, procedures and access control methodology and make sure you followed them. As with everything having documented evidence of anything you can is going to be your friend. So practical things like authentication information registers, encrypted passwords, approval and allocation processes that you can evidence are in operation. Work through recent hires for example and ensure the processes were followed and look for the gotchas. Is there an approval audit trail. When you log into the system that was approved does the users access match what was requested.

2. That you have rules, processes and you have followed them and have trained people

This is obvious but they are going to look that you have documented what you say you do, that you follow it and that you have trained people.

3. Documentation

They are going to look at audit trails and all your documentation and see that is classified and labelled. All the documents that you show them, as a minimum if they are confidential should be labelled as such. Is the document up to date. Has it been reviewed in the last 12 months. Does the version control match. Doing anything else would be a massive own goal.

Top 3 Mistakes People Make and How to Avoid Them

The top 3 Mistakes People Make For ISO 27001 Annex A 5.17 are

1. Share authentication information

There are circumstances where people know share authentication information and they do not need to. This is usually just lazy admin. The sharing of accounts where it doesn’t and should be needed.

2. Your temporary passwords are always the same

Giving first time passwords and making them unique may be a little tricky so often people rely on one password they always send out. Something like P@assw@rd. Do not do this.

3. Your document and version control is wrong

Keeping your document version control up to date, making sure that version numbers match where used, having a review evidenced in the last 12 months, having documents that have no comments in are all good practices.

Applicability across different business models

Business Type	Applicability & Interpretation	Examples of Control
Small Businesses	Password Hygiene & MFA. You likely don’t have a dedicated CISO. Compliance relies on forcing Multi-Factor Authentication (MFA) everywhere and ensuring staff don’t reuse personal passwords for work.	• Password Managers: Mandating the use of a business password manager (e.g., 1Password) to share credentials securely instead of emailing them. • No Post-its: A “Clean Desk Policy” check to ensure Wi-Fi or login passwords aren’t written on sticky notes attached to monitors.
Tech Startups	Secrets Management. Beyond user passwords, you manage API keys and SSH tokens. Auditors check if developers are hardcoding credentials into Git repositories (a major non-conformity).	• Environment Variables: Using tools like AWS Secrets Manager or HashiCorp Vault to inject keys at runtime, rather than storing them in code. • SSH Key Rotation: A policy requiring developers to rotate their SSH keys annually or immediately upon leaving the company.
AI Companies	Service Accounts & Data Lakes. AI training pipelines often run as “Service Accounts” with massive privileges. These non-human identities must be managed just as strictly as human users.	• Jupyter Notebook Hygiene: Scanning notebooks to ensure API keys for model providers (e.g., OpenAI) aren’t left in the cells before committing to shared repos. • Token Expiry: Using short-lived access tokens for data scientists accessing sensitive PII training buckets, rather than permanent access keys.

Applicable Laws and Related Standards

Framework / Law	Relevant Section / Control	Mapping Context & Implementation Focus
NIST CSF v2.0	PR.AA-P1 / PR.AA-P2	Focuses on identity management and authentication. Requires MFA and cryptographically secure storage of credentials.
NIS2 Directive (EU)	Article 21	Mandates security in network and information systems. Authentication is a minimum measure for essential and important entities.
DORA (EU)	Article 9	High-resilience authentication for financial entities to prevent unauthorised access to ICT systems.
SOC 2 (AICPA)	CC6.1 / CC6.3	Part of the Logical and Physical Access criteria. Focuses on identity verification and credential lifecycle management.
GDPR (EU)	Article 32	Defines appropriate technical and organisational measures. Weak authentication is often cited as a failure in data protection.
UK Data (Use and Access) Act 2025	Section 1 (Smart Data & Trust)	The evolution of GDPR focusing on reduced administrative burdens. Maintains high security thresholds for digital identity and secure data access.
Cyber Security and Resilience Bill (UK)	Supply Chain Security	The UK answer to NIS2. Expands mandatory reporting for MSPs and requires strong authentication to protect service management planes.
CIRCIA (USA)	Reporting Triggers	Mandatory 72-hour reporting for critical sectors. Assumes robust IAM is in place to accurately detect and report unauthorised access events.
EU AI Act	Article 15 (Cybersecurity)	Requires high-risk AI systems to be resilient against unauthorised third parties attempting to alter performance via credential theft.
ISO/IEC 42001 (AI)	Annex A 8.3	Maps AI system access to standard IAM. Protects the training data environment and model weights through strict authentication.
EU Product Liability Directive (PLD) Update	Article 6 (Defectiveness)	Extends strict liability to software. Insecure authentication, such as hardcoded passwords, can be deemed a product defect.
ECCF (European Cybersecurity Certification Framework)	Level Substantial	Move towards EU-wide harmonised security labels. Requires MFA and secure credential storage for certified products and services.
HIPAA (USA)	45 CFR § 164.312(a)(2)(i)	The Unique User Identification and Authentication standard required for protecting electronic Protected Health Information (ePHI).
CCPA / CPRA (California)	Section 1798.150	Provides a private right of action for breaches resulting from a failure to maintain reasonable security, specifically regarding credential protection.
PCI DSS v4.0	Requirement 8	Requires MFA for all access to the Cardholder Data Environment (CDE) and defines strict password complexity and rotation rules.

FAQ

Related ISO 27001 Controls and Further Reading

• ISO 27001 Annex A 8.21 Security of Network Services
• ISO 27001 Access Control Policy Beginner’s Guide

ISO 27001 controls and attribute values

Control type	Information security properties	Cybersecurity concepts	Operational capabilities	Security domains
Preventive	Confidentiality	Protect	Identity and access management	#Protection
	Integrity
	Availability

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