CWE-638

Class Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Draft MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Not Using Complete Mediation

Description

The product does not perform access checks on a resource every time the resource is accessed by an entity, which can create resultant weaknesses if that entity's rights or privileges change over time.

Consequences

Integrity, Confidentiality, Availability, Access Control, Other — Gain Privileges or Assume Identity, Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Read Application Data, Other

A user might retain access to a critical resource even after privileges have been revoked, possibly allowing access to privileged functionality or sensitive information, depending on the role of the resource.

Mitigations

Phase: Architecture and Design

Invalidate cached privileges, file handles or descriptors, or other access credentials whenever identities, processes, policies, roles, capabilities or permissions change. Perform complete authentication checks before accepting, caching and reusing data, dynamic content and code (scripts). Avoid caching access control decisions as much as possible.

Phase: Architecture and Design

Identify all possible code paths that might access sensitive resources. If possible, create and use a single interface that performs the access checks, and develop code standards that require use of this interface.