Authentication Cheat Sheet

= Introduction =

Authentication is the process of verification that an individual or an entity is who it claims to be. Authentication is commonly performed by submitting a user name or ID and one or more items of private information that only a given user should know.

Session Management is a process by which a server maintains the state of an entity interacting with it. This is required for a server to remember how to react to subsiquent requests throughout a transaction. Sessions are maintained on the server by a session identifier which can be passed back and forward between the client and server when mtransmitting and receiving requests. Sessions should be unique per user and computationally very difficult to predict.

For more information on Authentication, please see the OWASP Guide to Authentication page.

= Authentication General Guidelines =

Implement Proper Password Strength Controls
A key concern when using passwords for authentication is password strength. A "strong" password policy makes it difficult or even improbable for one to guess the password either by using manual or automated means. The following characteristics define strong a strong password:

1.Password Length

The longer the password the more combinations possible combinations of characters exist and is hence more difficult to guess.

Important applications: Minimum of 6 characters in length.

Critical applications: Minimum of 8 characters in length. (consider multi-factor authentication)

Highly critical applications: Consider multi-factor authentication

2. Password complexity

Example Passwords should be checked for the following composition or a variance of such:


 * at least: 1 uppercase character (A-Z)
 * at least: 1 lowercase character (a-z)
 * at least: 1 digit (0-9)
 * at least one special character (!"£$%&amp;...)
 * a defined minimum length (e.g. 8 chars)
 * a defined maximum length (as with all external input)
 * no contiguous characters (e.g. 123abcd)
 * not more than 2 identical characters in a row (1111)

Implement Secure Password Recovery Mechanism
Password recovery systems are difficult to secure against abuse, circumvention. The best way is to keep them as simple as possible.

Secret questions
Car,Date of Birth (DOB),Colour

Implement Account Lockout
= Session Management General Guidelines =

Cookie Security
= References =

= Authors and Primary Editors =

Eoin Keary eoinkeary[at]owasp.org