Description

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

Related Weaknesses

CWE-77
CWE-77
CWE-77

Consequences

Confidentiality, Integrity, Availability: Execute Unauthorized Code or Commands

Potential Mitigations

Phase: Implementation

Description: 

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

CVE References

• CVE-2006-2059
  • Executable regexp in PHP by inserting “e” modifier into first argument to preg_replace

• CVE-2005-3420
  • Executable regexp in PHP by inserting “e” modifier into first argument to preg_replace

• CVE-2006-2878
  • Complex curly syntax inserted into the replacement argument to PHP preg_replace(), which uses the “/e” modifier

• CVE-2006-2908
  • Function allows remote attackers to execute arbitrary PHP code via the username field, which is used in a preg_replace function call with a /e (executable) modifier.