CWE-166: Improper Handling of Missing Special Element

Description

The product receives input from an upstream component, but it does not handle or incorrectly handles when an expected special element is missing.

Abstraction: BaseA weakness specific enough to point to detection and prevention methods.
Likelihood of exploit: Not rated by MITRE
Status: Draft

Common consequences

Availability
DoS: Crash, Exit, or Restart

Potential mitigations

Developers should anticipate that special elements will be removed in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
ImplementationInput Validation
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...
ImplementationInput Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Related weaknesses

Parent weaknesses

CAPEC attack patterns that exploit it

CWE 4.20 links no CAPEC attack pattern to this weakness.

Potential mitigations

Developers should anticipate that special elements will be removed in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.

ImplementationInput Validation

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...

ImplementationInput Validation

Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.