Reliance on Cookies without Validation and Integrity Checking in a Security Decision

Opis

The product 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.

Skutki

• 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.

Zapobieganie

• Architecture and Design

  Avoid using cookie data for a security-related decision.

• Implementation

  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.

• Architecture and Design

  Add integrity checks to detect tampering.

• Architecture and Design

  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.

Przykłady podatności

• 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."

Słabość nadrzędna

• CWE-807 Reliance on Untrusted Inputs in a Security Decision
• CWE-565 Reliance on Cookies without Validation and Integrity Checking

Kiedy powstaje

• Implementation

Dotyczy

Not Language-Specific, Web Based, Web Server

Uwagi

A new parent might need to be defined for this entry. This entry is specific to cookies, which reflects the significant number of vulnerabilities being reported for cookie-based authentication in CVE during 2008 and 2009. However, other types of inputs - such as parameters or headers - could also be used for similar authentication or authorization. Similar issues (under the Research view) include CWE-247 and CWE-472.

Źródła

1. Unforgivable Vulnerabilities — Steve Christey, 2007
2. Writing Secure Code — Michael Howard, David LeBlanc, Chapter 13, "Sensitive Data in Cookies and Fields" Page 435, Microsoft Press, 2002