ISO 27001:2022 Annex A Control 8.5

Abstract of Annex A Control 8.5: Secure authentication

ISO 27001 Annex A Control 8.5 Secure authentication is a main component of information security that ensures only authorized users or entities can access systems, applications, and services. This control goes over the implementation of authentication technologies and procedures based on information access restrictions, reducing the risk of unauthorized access through authentication mechanisms.

Iso 27001 Annex A Control 8.5 Secure Authentication

Control Type

Information Security Properties

Cybersecurity Concepts

Operational Capabilities

Security Domains

Objective of Control 8.5

The objective of Control 8.5 is to verify the identity of users or systems before granting access to sensitive assets. Through implementing appropriate authentication measures, your organization can reduce the risk of unauthorized access, data breaches, and operational disruptions.

Purpose of Control 8.5

Secure authentication is for protecting your organization’s information assets. Authentication mechanisms ensure that only authorized individuals and systems can access specific resources based on predefined policies. 

The key purposes of secure authentication include:

  • Identity Assurance – Confirming that a user or system is who they claim to be before granting access.
  • Minimizing Unauthorized Access – Preventing attackers from exploiting weak or stolen credentials to gain unauthorized access to systems.
  • Reducing the Risk of Credential-Based Attacks – Implementing authentication methods that mitigate the risks of phishing, brute-force attacks, and password spraying.
  • Enhancing Multi-Layered Security – Strengthening authentication with multi-factor authentication (MFA) to increase security beyond passwords.
  • Improving User Accountability – Ensuring that every user action is tied to a verified identity, allowing for better auditability and forensic investigations.

Guidance for Implementing Secure Authentication

To implement secure authentication effectively, your organization should follow best practices and align authentication mechanisms with risk levels, system sensitivity, and user roles.

1. Selecting Suitable Authentication Techniques

The selection of authentication methods should be based on the sensitivity of the system and data being accessed. Your organization should consider:

  • Traditional authentication – Username and password combinations.
  • Two-factor authentication (2FA) and multi-factor authentication (MFA) – Adding layers of authentication through a combination of passwords, biometrics, security tokens, or one-time passcodes (OTP).
  • Passwordless authentication – Implementing certificate-based authentication, smart cards, or biometric authentication.
  • Context-aware authentication – Adjusting authentication requirements based on risk factors such as device location, IP address, or login behavior anomalies.

2. Implementing Multi-Factor Authentication (MFA)

MFA significantly strengthens authentication security by requiring two or more authentication factors. Your organization should:

  • Require MFA for privileged accounts and access to critical systems.
  • Combine different authentication factors:
    • Something you know (password, PIN).
    • Something you have (security token, smart card).
    • Something you are (biometric authentication like fingerprint or facial recognition).
  • Enforce adaptive authentication based on risk assessment (e.g., requiring MFA for logins from new devices or locations).

3. Secure Log-On Procedures

To reduce security risks during user authentication, your organization should:

  • Mask password entry to prevent shoulder surfing.
  • Limit authentication error messages to avoid giving attackers clues about valid credentials.
  • Implement CAPTCHA or account lockout mechanisms to prevent brute-force attacks.
  • Log and monitor authentication events to detect unauthorized access attempts.

4. Password Security and Management

To strengthen authentication security, your organization should:

  • Require complex passwords with length, randomness, and expiration policies.
  • Use password managers to reduce password reuse across systems.
  • Implement password hashing and encryption to secure stored credentials.
  • Prevent password transmission in clear text over networks.

5. Session Management

To prevent unauthorized access, your organization should:

  • Terminate inactive sessions automatically after a defined period of inactivity.
  • Limit session duration for high-risk applications.
  • Require reauthentication for critical transactions such as financial transfers or access to sensitive data.

Related ISO 27001 Controls

Secure authentication does not operate in isolation. Other controls that complement and support Control 8.5 include:

  • Control 5.15: Access Control – Ensures appropriate access rights are assigned to users.
  • Control 5.16: Identity Management – Manages user identities and authentication methods effectively.
  • Control 8.2: Privileged Access Management – Strengthens authentication for users with elevated access.
  • Control 8.3: Information Access Restriction – Enforces restrictions through secure authentication.
  • Control 8.4: Access to Source Code – Ensures secure authentication is applied to highly sensitive assets.

How Templates Can Help

Your organization can streamline the implementation of secure authentication with ready-to-use templates. These templates are made to align with ISO 27001 requirements, helping your organization save time.

  • Access Control Policy Template: Defines the principles of authentication and access control.
  • User Authentication Policy Template: Helps establish MFA and other authentication requirements.
  • Session Management Policy Template: Provides guidance for handling inactive sessions securely.
  • ISO 27001 Password Policy Template: Ensures strong password policies and management.

Additional Resources

To further strengthen your authentication strategy, you can refer to: