CWE-917

What is CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement (Expression Language Injection))?

The product constructs all or part of an expression language statement using externally-influenced input but does not neutralize special elements.

Vulnerability Insights

Improper Neutralization of Special Elements used in an Expression Language Statement (Expression Language Injection) (CWE-917) represents a significant security risk across modern software systems. This weakness enables attackers to exploit injection flaws in applications, potentially leading to unauthorized access, data exfiltration, or remote code execution. Organizations must implement defense-in-depth strategies combining static analysis, runtime monitoring, and binary analysis to detect and mitigate these vulnerabilities.

Impact on Systems

• System Compromise: Direct backend execution
• Data Exfiltration: Access to unauthorized records

Real-World Attack Scenario

The attacker recognizes an interface vulnerable to injection. They supply a concatenated malicious payload that breaks out of the expected data context and alters the interpreted logical command structure. The backend system executes the payload implicitly, granting the attacker unauthorized command or data access.

Code Examples

Vulnerable Implementation

const query = "SELECT * FROM data WHERE filter = '" + input + "'";
// VULNERABLE: Injection flaw
db.execute(query);

Secure Alternative

const query = "SELECT * FROM data WHERE filter = ?";
// SECURE: Parameterized execution
db.execute(query, [input]);

Detection with Precogs AI

Precogs AI detects expression language injection in Java applications and template engines by tracing user input to EL evaluation contexts. Our binary analysis engine examines compiled artifacts without requiring source code access, identifying CWE-917 patterns in vendor software, containers, firmware, and third-party libraries.

Remediation

Implement proper injection controls following secure coding guidelines. Use automated scanning tools like Precogs AI to continuously monitor for CWE-917 vulnerabilities across your software supply chain. Apply the principle of least privilege and validate all inputs from untrusted sources.