Description
The application uses a protection mechanism that relies on the existence or values of a cookie, but it does not properly ensure that the cookie 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. Attackers can bypass protection mechanisms such as authorization and authentication by modifying the cookie to contain an expected value.
Modes of Introduction:
– Architecture and Design
Likelihood of Exploit: High
Related Weaknesses
Consequences
Access Control: Bypass Protection Mechanism, Gain Privileges or Assume Identity
It is dangerous to use cookies to set a user’s privileges. The cookie can be manipulated to claim a high level of authorization, or to claim that successful authentication has occurred.
Potential Mitigations
Phase: Architecture and Design
Effectiveness:
Description:
Avoid using cookie data for a security-related decision.
Phase: Implementation
Effectiveness:
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
Effectiveness:
Description:
Add integrity checks to detect tampering.
Phase: Architecture and Design
Effectiveness:
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.
CVE References
- CVE-2009-1549
- Attacker can bypass authentication by setting a cookie to a specific value.
- CVE-2009-1619
- Attacker can bypass authentication and gain admin privileges by setting an “admin” cookie to 1.
- CVE-2009-0864
- Content management system allows admin privileges by setting a “login” cookie to “OK.”
- CVE-2008-5784
- e-dating application allows admin privileges by setting the admin cookie to 1.
- CVE-2008-6291
- Web-based email list manager allows attackers to gain admin privileges by setting a login cookie to “admin.”