COMMON WEAKNESS ENUMERATIONDraft

CWE-625

Permissive Regular Expression

The product uses a regular expression that does not sufficiently restrict the set of allowed values.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product uses a regular expression that does not sufficiently restrict the set of allowed values.

Extended description

This effectively causes the regexp to accept substrings that match the pattern, which produces a partial comparison to the target. In some cases, this can lead to other weaknesses. Common errors include: - not identifying the beginning and end of the target string - using wildcards instead of acceptable character ranges - others

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

This problem is frequently found when the regular expression is used in input validation or security features such as authentication.

Risk

What does successful exploitation lead to?

Bypass Protection Mechanism

Affected security scopes: Access Control

Defence

How is it prevented and fixed?

Implementation

Implementation-phase defence

Detail
When applicable, ensure that the regular expression marks beginning and ending string patterns, such as "/^string$/" for Perl.

Verification

How is it detected?

Automated Static Analysis

High
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.)
CWE-625: Common Weakness Enumeration Entry CWE-625 · DayBreach Sözlük · DayBreach