Testing for Weak password policy (OWASP-AT-008)
This article is part of the OWASP Testing Guide v4 (the current status is:DRAFT).
OWASP Testing Guide v4 Table of Contents [DRAFT] At the moment the The entire OWASP Testing Guide v3 can be downloaded here.
The most prevalent and most easily administered authentication mechanism is the humble password. The password represents the keys to the kingdom, but is often subverted by users in the name of usability. In each of the recent high profile hacks that have revealed user credentials, it is lamented that most common passwords are still: 123456, password and qwerty.
Determine the resistance of the application's to brute force password guessing using available password dictionaries by evaluating the length, complexity, reuse and aging requirements of passwords.
How to test
- What characters are permitted and forbidden for use within a password?
- How often can a user change their password?
- When must a user change their password? After 90 days? After account lockout due to excessive logon attempts?
- How often can a user reuse a password? Does the application store the user's previous 8 passwords?
- How different must the next password be from the last password (or however many are stored by the application)?
To mitigate the risk of easily guessed passwords facilitating unauthorised access there are two solutions: introduce additional authentication controls or introduce a password policy. The simplest and cheapest of these is the introduction of a password policy that ensures password length, complexity, reuse and aging.