---
notetype: reference
standard: ISO 27002
version: 2022
language: EN
type: control
id: "A.8.5"
title: "Secure authentication"
theme: Technological
control_type: [Preventive]
information_security_properties:
  - Confidentiality
  - Integrity
  - Availability
cybersecurity_concepts: [Protect]
operational_capabilities: [Identity_and_access_management]
security_domains: [Protection]
tags:
- iso27002/2022/EN
- sourcetext
status: active
---

## 8.5 Secure authentication

### Control
Secure authentication technologies and procedures should be implemented based on information access restrictions and the topic-specific policy on access control.

### Purpose
To ensure a user or an entity is securely authenticated, when access to systems, applications and services is granted.

### Guidance
A suitable authentication technique should be chosen to substantiate the claimed identity of a user, software, messages and other entities.

The strength of authentication should be appropriate for the classification of the information to be accessed. Where strong authentication and identity verification is required, authentication methods alternative to passwords, such as digital certificates, smart cards, tokens or biometric means, should be used.

Authentication information should be accompanied by additional authentication factors for accessing critical information systems (also known as multi-factor authentication). Using a combination of multiple authentication factors, such as what you know, what you have and what you are, reduces the possibilities for unauthorized accesses. Multi-factor authentication can be combine d with other techniques to require additional factors under specific circumstances, based on predefined rules and patterns, such as access from an unusual location, from an unusual device or at an unusual time.

Biometric authentication information should be invalidated if it is ever compromised. Biometric authentication can be unavailable depending on the conditions of use (e.g. moisture or aging). To prepare for these issues, biometric authentication should be accompanied with at least one alternative authentication technique.

The procedure for logging into a system or application should be designed to minimize the risk of unauthorized access. Log-on procedures and technologies should be implemented considering the following:

a\) not displaying sensitive system or application information until the log-on process has been successfully completed in order to avoid providing an unauthorized user with any unnecessary assistance;
b\) displaying a general notice warning that the system or the application or the service should only be accessed by authorized users;
c\) not providing help messages during the log-on procedure that would aid an unauthorized user (e.g. if an error condition arises, the system should not indicate which part of the data is correct or incorrect);
d\) validating the log-on information only on completion of all input data;
e\) protecting against brute force log-on attempts on usernames and passwords \[e.g. using completely automated public Turing test to tell computers and humans apart (CAPTCHA), requiring password reset after a predefined number of failed attempts or blocking the user after a maximum number of errors\];
f\) logging unsuccessful and successful attempts;
g\) raising a security event if a potential attempted or successful breach of log-on controls is detected (e.g. sending an alert to the user and the organization’s system administrators when a certain number of wrong password attempts has been reached);
h\) displaying or sending the following information on a separate channel on completion of a successful log-on:
 1\) date and time of the previous successful log-on;
 2\) details of any unsuccessful log-on attempts since the last successful log-on;
i\) not displaying a password in clear text when it is being entered; in some cases, it can be required to de-activate this functionality in order to facilitate user log-on (e.g. for accessibility reasons or to avoid blocking users because of repeated errors);
j\) not transmitting passwords in clear text over a network to avoid being captured by a network "sniffer” program;
k\) terminating inactive sessions after a defined period of inactivity, especially in high risk locations such as public or external areas outside the organization’s security management or on user endpoint devices;
l\) restricting connection duration times to provide additional security for high-risk applications and reduce the window of opportunity for unauthorized access.

### Other information
Additional information on entity authentication assurance can be found is ISO/IEC 29115.