CWE-1289: Improper Validation of Unsafe Equivalence in Input
Description
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.
- Abstraction
- BaseA weakness specific enough to point to detection and prevention methods.
- Likelihood of exploit
- Not rated by MITRE
- Status
- Incomplete
Common consequences
- Other
Varies by Context
Potential mitigations
- ImplementationInput ValidationEffectiveness: High
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...
Related weaknesses
CAPEC attack patterns that exploit it
CWE 4.20 links no CAPEC attack pattern to this weakness.