Name Accessing Functionality Not Properly Constrained by ACLs
Summary In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.
Prerequisites The application must be navigable in a manner that associates elements (subsections) of the application with ACLs. The various resources, or individual URLs, must be somehow discoverable by the attacker The administrator must have forgotten to associate an ACL or has associated an inappropriately permissive ACL with a particular navigable resource.
Solutions In a more general setting, the administrator must mark every resource besides the ones supposed to be exposed to the user as accessible by a role impossible for the user to assume. The default security setting must be to deny access and then grant access only to those resources intended by business logic.
Related Weaknesses
CWE ID Description
CWE-276 Incorrect Default Permissions
CWE-285 Improper Authorization
CWE-434 Unrestricted Upload of File with Dangerous Type
CWE-693 Protection Mechanism Failure
CWE-721 OWASP Top Ten 2007 Category A10 - Failure to Restrict URL Access
CWE-732 Incorrect Permission Assignment for Critical Resource
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