CWE-793: Only Filtering One Instance of a Special Element
Learn about CWE-793 (Only Filtering One Instance of a Special Element), its security impact, exploitation methods, and prevention guidelines.
What is Only Filtering One Instance of a Special Element?
• Overview: This vulnerability occurs when software only filters one occurrence of a special element (such as a script tag or SQL command) in incoming data, which can allow malicious elements to pass through if they appear multiple times.
• Exploitation Methods:
- Attackers can exploit this by inserting multiple instances of a malicious element, knowing that only one will be filtered.
- Common attack patterns include injecting multiple script tags for XSS or multiple SQL commands for SQL injection.
• Security Impact:
- Direct consequences include the execution of arbitrary code or unauthorized database access.
- Potential cascading effects include data breaches, system compromise, and unauthorized actions within the application.
- Business impact can include loss of customer trust, legal consequences, and financial penalties.
• Prevention Guidelines:
- Specific code-level fixes include ensuring all instances of a special element are filtered or sanitized, not just the first or last.
- Security best practices involve thorough input validation and output encoding for all user-supplied data.
- Recommended tools and frameworks include using well-maintained libraries for input validation and employing security-focused coding standards and automated testing tools.
Technical Details
Likelihood of Exploit: Not specified
Affected Languages: Not specified
Affected Technologies: Not specified