CWE-624 Detail

The product uses a regular expression that either (1) contains an executable component with user-controlled inputs, or (2) allows a user to enable execution by inserting pattern modifiers.

Case (2) is possible in the PHP preg_replace() function, and possibly in other languages when a user-controlled input is inserted into a string that is later parsed as a regular expression.

Modes Of Introduction

Implementation

Applicable Platforms

Language

Name: PHP (Undetermined)
Name: Perl (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : Implementation
The regular expression feature in some languages allows inputs to be quoted or escaped before insertion, such as \Q and \E in Perl.

Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Vulnerability Mapping Notes

Justification : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : 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.

NotesNotes

Under-studied. The existing PHP reports are limited to highly skilled researchers, but there are few examples for other languages. It is suspected that this is under-reported for all languages. Usability factors might make it more prevalent in PHP, but this theory has not been investigated.

Submission

Modifications