CWE-493: Critical Public Variable Without Final Modifier | Glexia
CWE-493 (Critical Public Variable Without Final Modifier) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK context.
Glexia's Take · Automated analysis
CWE-493: Critical Public Variable Without Final Modifier
Critical Public Variable Without Final Modifier represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Integrity: Modify Application Data: The object could potentially be tampered with.
- Confidentiality: Read Application Data: The object could potentially allow the object to be read.
Developer Pattern
CWE-493 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-493, 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-493: Critical Public Variable Without Final Modifier
The product has a critical public variable that is not final, which allows the variable to be modified to contain unexpected values.
If a field is non-final and public, it can be changed once the value is set by any function that has access to the class which contains the field. This could lead to a vulnerability if other parts of the program make assumptions about the contents of that field.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Suppose this WidgetData class is used for an e-commerce web site. The programmer attempts to prevent price-tampering attacks by setting the price of the widget using the constructor. The price field is not final. Even though the value is set by the constructor, it could be modified by anybody that has access to an instance of WidgetData.
- Assume the following code is intended to provide the location of a configuration file that controls execution of the application. While this field is readable from any function, and thus might allow an information leak of a pathname, a more serious problem is that it can be changed by any function.
Remediation
- Implementation: Declare all public fields as final when possible, especially if it is used to maintain internal state of an Applet or of classes used by an Applet. If a field must be public, then perform all appropriate sanity checks before accessing the field from your code.
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
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.