The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

When product performs a security-critical calculation incorrectly, it might lead to incorrect resource allocations, incorrect privilege assignments, or failed comparisons among other things. Many of the direct results of an incorrect calculation can lead to even larger problems such as failed protection mechanisms or even arbitrary code execution.

Modes Of Introduction

Implementation

Applicable Platforms

Language

Class: Not Language-Specific (Undetermined)

Technologies

Class: Not Technology-Specific (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : Implementation
Understand your programming language's underlying representation and how it interacts with numeric calculation. Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how your language handles numbers that are too large or too small for its underlying representation.
Phases : 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.
Phases : Implementation
Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity.
Phases : Architecture and Design

Use languages, 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++).

Phases : Architecture and Design

Use languages, 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++).

Phases : Implementation
Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system.
Phases : Testing
Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Phases : Testing
Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Detection Methods

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Specifically, manual static analysis is useful for evaluating the correctness of allocation calculations. This can be useful for detecting overflow conditions (CWE-190) or similar weaknesses that might have serious security impacts on the program.

Effectiveness : High

Vulnerability Mapping Notes

Rationale : This CWE entry is extremely high-level, a Pillar. In many cases, lower-level children or descendants are more appropriate. However, sometimes this weakness is forced to be used due to the lack of in-depth weakness research. See Research Gaps.
Comments : Where feasible, consider children or descendants of this entry instead.

Related Attack Patterns

Notes

Weaknesses related to this Pillar appear to be under-studied, especially with respect to classification schemes. Input from academic and other communities could help identify and resolve gaps or organizational difficulties within CWE.

References

REF-106

SafeInt
David LeBlanc, Niels Dekker.
http://safeint.codeplex.com/

REF-44

24 Deadly Sins of Software Security
Michael Howard, David LeBlanc, John Viega.

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

Submission

Modifications