CWE-627

Variant 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 Incomplete 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
Dynamic Variable Evaluation

Description

In a language where the user can influence the name of a variable at runtime, if the variable names are not controlled, an attacker can read or write to arbitrary variables, or access arbitrary functions.

The resultant vulnerabilities depend on the behavior of the application, both at the crossover point and in any control/data flow that is reachable by the related variables or functions.

Consequences

Confidentiality, Integrity, Availability — Modify Application Data, Execute Unauthorized Code or Commands

An attacker could gain unauthorized access to internal program variables and execute arbitrary code.

Mitigations

Phase: Implementation

Refactor the code to avoid dynamic variable evaluation whenever possible.

Phase: Implementation

Use only allowlists of acceptable variable or function names.

Phase: Implementation

For function names, ensure that you are only calling functions that accept the proper number of arguments, to avoid unexpected null arguments.