VariantDraftCWE-176

CWE-176: Improper Handling of Unicode Encoding

Description

The product does not properly handle when an input contains Unicode encoding.

Abstraction: VariantA weakness tied to a specific language, technology or resource.
Likelihood of exploit: Not rated by MITRE
Status: Draft

Common consequences

Integrity
Unexpected State

Potential mitigations

Architecture and DesignInput Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
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

CWE-172Encoding Error

CAPEC attack patterns that exploit it

CAPEC-71Using Unicode Encoding to Bypass Validation Logic

Potential mitigations

Architecture and DesignInput Validation

Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.

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.