CWE-1289: Improper Validation of Unsafe Equivalence in… | Glexia
CWE-1289 (Improper Validation of Unsafe Equivalence in Input) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK…
Glexia's Take · Automated analysis
CWE-1289: Improper Validation of Unsafe Equivalence in Input
Improper Validation of Unsafe Equivalence in Input represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Other: Varies by Context
Developer Pattern
CWE-1289 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-1289, 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-1289: Improper Validation of Unsafe Equivalence in Input
The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
Attackers can sometimes bypass input validation schemes by finding inputs that appear to be safe, but will be dangerous when processed at a lower layer or by a downstream component. For example, a simple XSS protection mechanism might try to validate that an input has no "<script>" tags using case-sensitive matching, but since HTML is case-insensitive when processed by web browsers, an attacker could inject "<ScrIpT>" and trigger XSS.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Missing validation
- Unsafe defaults
- Insufficient authorization or memory-safety invariant
Remediation
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Detection
- Code review
- SAST
- DAST
- Focused regression tests
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.