Détail du CWE-647

The product defines policy namespaces and makes authorization decisions based on the assumption that a URL is canonical. This can allow a non-canonical URL to bypass the authorization.

If an application defines policy namespaces and makes authorization decisions based on the URL, but it does not require or convert to a canonical URL before making the authorization decision, then it opens the application to attack. For example, if the application only wants to allow access to http://www.example.com/mypage, then the attacker might be able to bypass this restriction using equivalent URLs such as:

• http://WWW.EXAMPLE.COM/mypage
• http://www.example.com/%6Dypage (alternate encoding)
• http://192.168.1.1/mypage (IP address)
• http://www.example.com/mypage/ (trailing /)
• http://www.example.com:80/mypage

Therefore it is important to specify access control policy that is based on the path information in some canonical form with all alternate encodings rejected (which can be accomplished by a default deny rule).

Modes d'introduction

Implementation : REALIZATION: This weakness is caused during implementation of an architectural security tactic.
Operation

Plateformes applicables

Langue

Class: Not Language-Specific (Undetermined)

Technologies

Name: Web Server (Undetermined)

Conséquences courantes

Mesures d’atténuation potentielles

Phases : Architecture and Design
Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form.
Phases : Architecture and Design
Reject all alternate path encodings that are not in the expected canonical form.

Méthodes de détection

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Efficacité : High

Notes de cartographie des vulnérabilités

Justification : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Commentaire : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Soumission

Modifications