CWE-917: Improper Neutralization of Special Elements used… | Glexia
CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')) weakness overview with…
Glexia's Take · Automated analysis
CWE-917: EL Injection
Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Confidentiality: Read Application Data
- Integrity: Execute Unauthorized Code or Commands
Developer Pattern
CWE-917 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-917, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
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 (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.
Frameworks such as Java Server Page (JSP) allow a developer to insert executable expressions within otherwise-static content. When the developer is not aware of the executable nature of these expressions and/or does not disable them, then if an attacker can inject expressions, this could lead to code execution or other unexpected behaviors.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Missing validation
- Unsafe defaults
- Insufficient authorization or memory-safety invariant
Remediation
- Architecture and Design: Avoid adding user-controlled data into an expression interpreter when possible.
- Implementation:
- System Configuration,Operation: The framework or tooling might allow the developer to disable or deactivate the processing of EL expressions, such as setting the isELIgnored attribute for a JSP page to "true".
Detection
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
- CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine
- CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
- CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
- CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
- CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.