Incorrect CalculationID: 682 | Date: (C)2012-05-14 (M)2022-10-10 |
Type: weakness | Status: DRAFT |
Abstraction Type: Class |
Description
The software performs a calculation that generates incorrect or
unintended results that are later used in security-critical decisions or
resource management.
Extended DescriptionWhen software 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.
Likelihood of Exploit: High
Applicable PlatformsLanguage Class: All
Time Of Introduction
- Architecture and Design
- Implementation
Related Attack Patterns
Common Consequences
Scope | Technical Impact | Notes |
---|
Availability | DoS: crash / exit /
restart | If the incorrect calculation causes the program to move into an
unexpected state, it may lead to a crash or impairment of
service. |
IntegrityConfidentialityAvailability | DoS: crash / exit /
restartDoS: resource consumption
(other)Execute unauthorized code or
commands | If the incorrect calculation is used in the context of resource
allocation, it could lead to an out-of-bounds operation (CWE-119)
leading to a crash or even arbitrary code execution. Alternatively, it
may result in an integer overflow (CWE-190) and / or a resource
consumption problem (CWE-400). |
Access_Control | Gain privileges / assume
identity | In the context of privilege or permissions assignment, an incorrect
calculation can provide an attacker with access to sensitive
resources. |
Access_Control | Bypass protection
mechanism | If the incorrect calculation leads to an insufficient comparison
(CWE-697), it may compromise a protection mechanism such as a validation
routine and allow an attacker to bypass the security-critical
code. |
Detection Methods
Name | Description | Effectiveness | Notes |
---|
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. | High | |
Potential Mitigations
Phase | Strategy | Description | Effectiveness | Notes |
---|
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. | | |
Implementation | Input Validation | 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. | | |
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. | | |
Architecture and Design | Language SelectionLibraries or Frameworks | 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++). | | |
Implementation | Compilation or Build Hardening | 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. | | |
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. | | |
Testing | | Use dynamic tools and techniques that interact with the software using
large test suites with many diverse inputs, such as fuzz testing
(fuzzing), robustness testing, and fault injection. The software's
operation may slow down, but it should not become unstable, crash, or
generate incorrect results. | | |
Relationships
Related CWE | Type | View | Chain |
---|
CWE-682 ChildOf CWE-907 | Category | CWE-888 | |
Demonstrative Examples (Details)
- The following image processing code allocates a table for
images. (Demonstrative Example Id DX-33)
- This code attempts to calculate a football team's average number of
yards gained per touchdown.
- This example attempts to calculate the position of the second byte
of a pointer. (Demonstrative Example Id DX-55)
White Box Definitions None
Black Box Definitions None
Taxynomy Mappings
Taxynomy | Id | Name | Fit |
---|
CERT C Secure Coding | FLP32-C | Prevent or detect domain and range errors in math
functions | |
CERT C Secure Coding | FLP33-C | Convert integers to floating point for floating point
operations | |
CERT C Secure Coding | INT07-C | Use only explicitly signed or unsigned char type for numeric
values | |
CERT C Secure Coding | INT13-C | Use bitwise operators only on unsigned
operands | |
CERT C++ Secure Coding | INT07-CPP | Use only explicitly signed or unsigned char type for numeric
values | |
CERT C++ Secure Coding | INT10-CPP | Do not assume a positive remainder when using the %
operator | |
CERT C++ Secure Coding | INT13-CPP | Use bitwise operators only on unsigned
operands | |
CERT C++ Secure Coding | FLP32-CPP | Prevent or detect domain and range errors in math
functions | |
CERT C++ Secure Coding | FLP33-CPP | Convert integers to floating point for floating point
operations | |
References:
- David LeBlanc Niels Dekker .SafeInt.
- Michael Howard David LeBlanc John Viega .24 Deadly Sins of Software Security. McGraw-Hill. Section:'"Sin 7: Integer Overflows." Page 119'. Published on 2010.
- Mark Dowd John McDonald Justin Schuh .The Art of Software Security Assessment 1st Edition. Addison Wesley. Section:'Chapter 6, "Signed Integer Boundaries", Page
220.'. Published on 2006.