PillarDraftCWE-682

CWE-682: Incorrect Calculation

Description

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.

Abstraction: PillarThe most abstract kind of weakness: a theme that groups classes.
Likelihood of exploit: High
Status: Draft

Common consequences

Availability
DoS: Crash, Exit, or 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, or Restart; DoS: 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 or 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.

Potential mitigations

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.
ImplementationInput 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 DesignLanguage Selection
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++).
Architecture and DesignLibraries 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++).
ImplementationCompilation 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.

Related weaknesses

Child weaknesses

Can lead to

CWE-170Improper Null Termination

CAPEC attack patterns that exploit it

Description

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

Common consequences

Availability

DoS: Crash, Exit, or 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, or Restart; DoS: 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 or 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.

Potential mitigations

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.

ImplementationInput 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 DesignLanguage Selection

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++).

Architecture and DesignLibraries or Frameworks

ImplementationCompilation 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.