CWE WEAKNESSES  /  CWE-289

CWE-289

Authentication Bypass by Alternate Name

What it is

The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.

Impact

Mitigations

• [Architecture and Design] Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
• [Implementation]Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.When performing input validation, consider all potentially relevant properties, including length, type of input, the full r
• [Implementation] Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Real-world CVE examples

• CVE-2003-0317 — Protection mechanism that restricts URL access can be bypassed using URL encoding.
• CVE-2004-0847 — web framework for .NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash)

Related weaknesses

Source: MITRE CWE. View on cwe.mitre.org →