CWE-645: Overly Restrictive Account Lockout Mechanism

How it's found

Overly Restrictive Account Lockout Mechanism is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.

Account lockout is a security feature often present in applications as a countermeasure to the brute force attack on the password based authentication mechanism of the system. After a certain number of failed login attempts, the users' account may be disabled for a certain period of time or until it is unlocked by an administrator. Other security events may also possibly trigger account lockout. However, an attacker may use this very security feature to deny service to legitimate system users. It is therefore important to ensure that the account lockout security mechanism is not overly restrictive.

Consequences

• DoS: Resource Consumption (Other): Users could be locked out of accounts.

Mitigations

• Architecture and Design: Implement more intelligent password throttling mechanisms such as those which take IP address into account, in addition to the login name.
• Architecture and Design: Implement a lockout timeout that grows as the number of incorrect login attempts goes up, eventually resulting in a complete lockout.
• Architecture and Design: Consider alternatives to account lockout that would still be effective against password brute force attacks, such as presenting the user machine with a puzzle to solve (makes it do some computation).

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Class weakness
  CWE-287: Improper Authentication