CWE-791: Incomplete Filtering of Special Elements
Learn about CWE-791 (Incomplete Filtering of Special Elements), its security impact, exploitation methods, and prevention guidelines.
What is Incomplete Filtering of Special Elements?
• Overview: Incomplete Filtering of Special Elements occurs when an application receives data from an upstream source and fails to adequately filter out special characters or elements before passing it on to a downstream component, which can lead to security vulnerabilities.
• Exploitation Methods:
- Attackers can exploit this vulnerability by injecting special characters or elements that are interpreted in unintended ways by the downstream component, potentially leading to code execution or data corruption.
- Common attack patterns include SQL injection, cross-site scripting (XSS), and command injection, where special characters like quotes, angle brackets, or semicolons are used to alter the intended logic or data flow.
• Security Impact:
- Direct consequences of successful exploitation can include unauthorized access, data breaches, or execution of arbitrary code.
- Potential cascading effects may involve the compromise of additional systems or data, escalation of privileges, or denial of service.
- Business impact could be severe, including loss of customer trust, legal liabilities, and financial losses due to data theft or service outages.
• Prevention Guidelines:
- Specific code-level fixes include implementing rigorous input validation and output encoding to ensure that only expected and safe characters are processed.
- Security best practices involve using parameterized queries, escaping special characters, and adopting a principle of least privilege to minimize the impact of potential vulnerabilities.
- Recommended tools and frameworks include static code analysis tools to detect filtering flaws, and security libraries or frameworks specifically designed for input validation and sanitization.
Technical Details
Likelihood of Exploit: Not specified
Affected Languages: Not specified
Affected Technologies: Not specified