COMMON WEAKNESS ENUMERATIONIncomplete

CWE-1024

Comparison of Incompatible Types

The product performs a comparison between two entities, but the entities are of different, incompatible types that cannot be guaranteed to provide correct results when they are directly compared.

Abstraction

Class

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product performs a comparison between two entities, but the entities are of different, incompatible types that cannot be guaranteed to provide correct results when they are directly compared.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

In languages that are strictly typed but support casting/conversion, such as C or C++, the programmer might assume that casting one entity to the same type as another entity will ensure that the comparison will be performed correctly, but this cannot be guaranteed. In languages that are not strictly typed, such as PHP or JavaScript, there may be implicit casting/conversion to a type that the programmer is unaware of, causing unexpected results; for example, the string "123" might be converted to a number type.

Risk

What does successful exploitation lead to?

Varies by Context

Affected security scopes: Other

Defence

How is it prevented and fixed?

  • Follow secure coding guidelines for input handling and boundary checking.
  • Enforce strict security reviews and automated static analysis (SAST) checks.

Verification

How is it detected?

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Manual Static Analysis

Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.
CWE-1024: Common Weakness Enumeration Entry CWE-1024