CWE-190: Integer Overflow or Wraparound

MITRE CWE weakness

Description

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Common consequences

• Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (Memory), DoS: Instability
• Integrity: Modify Memory
• Confidentiality, Availability, Access Control: Execute Unauthorized Code or Commands, Bypass Protection Mechanism
• Availability, Other: Alter Execution Logic, DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU)
• Access Control: Bypass Protection Mechanism

Mitigations

Requirements — Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.

Requirements — Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.

Architecture and Design — Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]

Implementation — Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range. Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.

Implementation — Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7] Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.

References

• CWE page: https://cwe.mitre.org/data/definitions/190.html
• CWE list: https://cwe.mitre.org/data/index.html