VariantDraftCWE-152

CWE-152: Improper Neutralization of Macro Symbols

Description

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as macro symbols when they are sent to a downstream component.

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

ImplementationInput Validation
Developers should anticipate that macro symbols will be injected/removed/manipulated 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...
ImplementationOutput Encoding
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this...
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-138Improper Neutralization of Special Elements

CAPEC attack patterns that exploit it

CWE 4.20 links no CAPEC attack pattern to this weakness.

Potential mitigations

ImplementationInput Validation

Developers should anticipate that macro symbols will be injected/removed/manipulated 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...

ImplementationOutput Encoding

Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this...

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.