CWE-777: Regular Expression without Anchors
Learn about CWE-777 (Regular Expression without Anchors), its security impact, exploitation methods, and prevention guidelines.
What is Regular Expression without Anchors?
• Overview: Regular Expression without Anchors (CWE-777) is a vulnerability where a regular expression is used for input validation or neutralization, but it is not properly anchored. This means that the regex can match patterns anywhere in the input string, allowing attackers to potentially insert malicious data before or after the matched pattern.
• Exploitation Methods:
- Attackers can exploit this vulnerability by inserting malicious payloads before or after the pattern that the regular expression is intended to match.
- Common attack patterns include injecting SQL commands, scripting code, or other malicious data that can bypass weak input validation.
• Security Impact:
- Direct consequences include the acceptance of malicious or malformed data that should have been rejected.
- Potential cascading effects can lead to further attacks such as SQL injection, cross-site scripting (XSS), or remote code execution.
- Business impact includes compromised system integrity, data breaches, and potential legal and financial repercussions.
• Prevention Guidelines:
- Specific code-level fixes include using anchors (e.g., ^ for start and $ for end) in regular expressions to ensure the entire input is validated, not just parts of it.
- Security best practices involve thorough input validation, using allowlists, and employing regular expression anchors to enforce strict matching criteria.
- Recommended tools and frameworks include static analysis tools to detect regex issues and secure coding libraries that provide pre-validated input functions.
Technical Details
Likelihood of Exploit:
Affected Languages: Not specified
Affected Technologies: Not specified
Regular expressions are typically used to match a pattern of text. Anchors are used in regular expressions to specify where the pattern should match: at the beginning, the end, or both (the whole input).