What is the authoritative source for CWE-784?

Reliance on Cookies without Validation and Integrity Checking in a Security Decision (CWE-784) is catalogued in MITRE CWE and curated for EU compliance use cases by SQUR.

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CWE-784Reliance on Cookies without Validation and Integrity Checking in a Security Decision

Category: other

Description

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.

Common consequences· 1

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· 4

[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.