CWE-627 Dynamic Variable Evaluation

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.

• Confidentiality, Integrity, Availability: Modify Application Data, Execute Unauthorized Code or Commands, Varies by Context — An attacker could gain unauthorized read or write access to internal program variables and possibly execute arbitrary code. 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.

• [Implementation] Refactor the code to avoid dynamic variable evaluation whenever possible. • [Implementation] Use only allowlists of acceptable variable or function names. • [Implementation] For function names, ensure that you are only calling functions that accept the proper number of arguments, to avoid unexpected null arguments.

• CVE-2009-0422: Chain: Dynamic variable evaluation allows resultant remote file inclusion and path traversal. • CVE-2007-2431: Chain: dynamic variable evaluation in PHP program used to modify critical, unexpected $_SERVER variable for resultant XSS. • CVE-2006-4904: Chain: dynamic variable evaluation in PHP program used to conduct remote file inclusion. • CVE-2006-4019: Dynamic variable evaluation in mail program allows reading and modifying attachments and preferences of other users.