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 can introduce other weaknesses when the calculation is used for resource management or execution control.

An integer overflow or wraparound 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 wrap to become a very small or negative number. While this may be intended behavior in circumstances that rely on wrapping, it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs. This becomes security-critical when the result is used to control looping, make a security decision, or determine the offset or size in behaviors such as memory allocation, copying, concatenation, etc.

Modes Of Introduction

Implementation

Applicable Platforms

Language

Class: Not Language-Specific (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : 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.
Phases : 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.

Phases : 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.

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]

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.

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.

Phases : 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.

Phases : Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
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.

Detection Methods

Automated Static Analysis

This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.
Effectiveness : High

Black Box

Sometimes, evidence of this weakness can be detected using 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.
Effectiveness : Moderate

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

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Vulnerability Mapping Notes

Rationale : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Related Attack Patterns

Notes

Integer overflows can be primary to buffer overflows.
"Integer overflow" is sometimes used to cover several types of errors, including signedness errors, or buffer overflows that involve manipulation of integer data types instead of characters. Part of the confusion results from the fact that 0xffffffff is -1 in a signed context. Other confusion also arises because of the role that integer overflows have in chains.

References

REF-145

An overview of common programming security vulnerabilities and possible solutions
Yves Younan.
http://fort-knox.org/thesis.pdf

REF-146

Basic Integer Overflows
blexim.
http://www.phrack.org/issues.html?issue=60&id=10#article

REF-7

Writing Secure Code
Michael Howard, David LeBlanc.
https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223

REF-44

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

REF-106

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

REF-150

Top 25 Series - Rank 17 - Integer Overflow Or Wraparound
Johannes Ullrich.
http://software-security.sans.org/blog/2010/03/18/top-25-series-rank-17-integer-overflow-or-wraparound

REF-62

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

Submission

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