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.
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| ChildOf | Allowed | B | 914 | Improper Control of Dynamically-Identified Variables |
| PeerOf | Allowed | B | 183 | Permissive List of Allowed Inputs |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | V | 884 | CWE Cross-section |
| MemberOf | Prohibited | C | 990 | SFP Secondary Cluster: Tainted Input to Command |
| MemberOf | Prohibited | C | 1409 | Comprehensive Categorization: Injection |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | BS | BOSS-250 | Weaknesses in Software Written in Perl |
| MemberOf | Prohibited | BS | BOSS-279 | Input Validation Strategy |
| MemberOf | Prohibited | BS | BOSS-281 | Refactoring Strategy |
| MemberOf | Prohibited | BS | BOSS-311 | Execute Unauthorized Code or Commands (impact) |
| MemberOf | Prohibited | BS | BOSS-318 | Modify Application Data (impact) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 990 | SFP Secondary Cluster: Tainted Input to Command |
Many interpreted languages support the use of a "$$varname" construct to set a variable whose name is specified by the $varname variable. In PHP, these are referred to as "variable variables." Functions might also be invoked using similar syntax, such as $$funcname(arg1, arg2).
| Scope | Likelihood | Impact | Note |
|---|---|---|---|
| ConfidentialityIntegrityAvailability | N/A | Modify Application DataExecute Unauthorized Code or Commands | An attacker could gain unauthorized access to internal program variables and execute arbitrary code. |
An attacker could gain unauthorized access to internal program variables and execute arbitrary code.
Refactor the code to avoid dynamic variable evaluation whenever possible.
Use only allowlists of acceptable variable or function names.
For function names, ensure that you are only calling functions that accept the proper number of arguments, to avoid unexpected null arguments.
N/A
| Reference | Description |
|---|---|
| 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. |
| Ordinality | Description |
|---|---|
| Primary | N/A |
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.
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.
Under-studied, probably under-reported. Few researchers look for this issue; most public reports are for PHP, although other languages are affected. This issue is likely to grow in PHP as developers begin to implement functionality in place of register_globals.
N/A
| Taxonomy Name | Entry ID | Fit | Entry Name |
|---|
| ID | Name |
|---|