Description
The application relies on the existence or values of cookies when performing security-critical operations, but it does not properly ensure that the setting is valid for the associated user.
Attackers can easily modify cookies, within the browser or by implementing the client-side code outside of the browser. Reliance on cookies without detailed validation and integrity checking can allow attackers to bypass authentication, conduct injection attacks such as SQL injection and cross-site scripting, or otherwise modify inputs in unexpected ways.
Modes of Introduction:
– Architecture and Design
Related Weaknesses
Consequences
Access Control: Gain Privileges or Assume Identity
It is dangerous to use cookies to set a user’s privileges. The cookie can be manipulated to escalate an attacker’s privileges to an administrative level.
Potential Mitigations
Phase: Architecture and Design
Description:
Avoid using cookie data for a security-related decision.
Phase: Implementation
Description:
Perform thorough input validation (i.e.: server side validation) on the cookie data if you’re going to use it for a security related decision.
Phase: Architecture and Design
Description:
Add integrity checks to detect tampering.
Phase: Architecture and Design
Description:
Protect critical cookies from replay attacks, since cross-site scripting or other attacks may allow attackers to steal a strongly-encrypted cookie that also passes integrity checks. This mitigation applies to cookies that should only be valid during a single transaction or session. By enforcing timeouts, you may limit the scope of an attack. As part of your integrity check, use an unpredictable, server-side value that is not exposed to the client.