CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-369: Divide By Zero

Weakness ID: 369
Abstraction: Base
Status: Draft
Presentation Filter:
+ Description

Description Summary

The product divides a value by zero.

Extended Description

This weakness typically occurs when an unexpected value is provided to the product, or if an error occurs that is not properly detected. It frequently occurs in calculations involving physical dimensions such as size, length, width, and height.

+ Time of Introduction
  • Implementation
+ Common Consequences
ScopeEffect
Availability

Technical Impact: DoS: crash / exit / restart

A Divide by Zero results in a crash.

+ Likelihood of Exploit

Medium

+ Demonstrative Examples

Example 1

The following Java example contains a function to compute an average but does not validate that the input value used as the denominator is not zero. This will create an exception for attempting to divide by zero. If this error is not handled by Java exception handling, unexpected results can occur.

(Bad Code)
Example Language: Java 
public int computeAverageResponseTime (int totalTime, int numRequests) {
return totalTime / numRequests;
}

By validating the input value used as the denominator the following code will ensure that a divide by zero error will not cause unexpected results. The following Java code example will validate the input value, output an error message, and throw an exception.

(Good Code)
 
public int computeAverageResponseTime (int totalTime, int numRequests) throws ArithmeticException {
if (numRequests == 0) {
System.out.println("Division by zero attempted!");
throw ArithmeticException;
}
return totalTime / numRequests;
}

Example 2

The following C/C++ example contains a function that divides two numeric values without verifying that the input value used as the denominator is not zero. This will create an error for attempting to divide by zero, if this error is not caught by the error handling capabilities of the language, unexpected results can occur.

(Bad Code)
Example Languages: C and C++ 
double divide(double x, double y){
return x/y;
}

By validating the input value used as the denominator the following code will ensure that a divide by zero error will not cause unexpected results. If the method is called and a zero is passed as the second argument a DivideByZero error will be thrown and should be caught by the calling block with an output message indicating the error.

(Good Code)
 
const int DivideByZero = 10;
double divide(double x, double y){
if ( 0 == y ){
throw DivideByZero;
}
return x/y;
}
...
try{
divide(10, 0);
}
catch( int i ){
if(i==DivideByZero) {
cerr<<"Divide by zero error";
}
}

Example 3

The following C# example contains a function that divides two numeric values without verifying that the input value used as the denominator is not zero. This will create an error for attempting to divide by zero, if this error is not caught by the error handling capabilities of the language, unexpected results can occur.

(Bad Code)
Example Language: C# 
int Division(int x, int y){
return (x / y);
}

The method can be modified to raise, catch and handle the DivideByZeroException if the input value used as the denominator is zero.

(Good Code)
 
int SafeDivision(int x, int y){
try{
return (x / y);
}
catch (System.DivideByZeroException dbz){
System.Console.WriteLine("Division by zero attempted!");
return 0;
}
}

Example 3 References:

+ Observed Examples
ReferenceDescription
Invalid size value leads to divide by zero.
"Empty" content triggers divide by zero.
Height value of 0 triggers divide by zero.
+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class682Incorrect Calculation
Development Concepts (primary)699
Research Concepts (primary)1000
Weaknesses for Simplified Mapping of Published Vulnerabilities (primary)1003
ChildOfCategoryCategory730OWASP Top Ten 2004 Category A9 - Denial of Service
Weaknesses in OWASP Top Ten (2004) (primary)711
ChildOfCategoryCategory738CERT C Secure Coding Section 04 - Integers (INT)
Weaknesses Addressed by the CERT C Secure Coding Standard (primary)734
ChildOfCategoryCategory739CERT C Secure Coding Section 05 - Floating Point (FLP)
Weaknesses Addressed by the CERT C Secure Coding Standard734
ChildOfCategoryCategory848CERT Java Secure Coding Section 03 - Numeric Types and Operations (NUM)
Weaknesses Addressed by the CERT Java Secure Coding Standard (primary)844
ChildOfCategoryCategory872CERT C++ Secure Coding Section 04 - Integers (INT)
Weaknesses Addressed by the CERT C++ Secure Coding Standard (primary)868
ChildOfCategoryCategory873CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)
Weaknesses Addressed by the CERT C++ Secure Coding Standard868
ChildOfCategoryCategory998SFP Secondary Cluster: Glitch in Computation
Software Fault Pattern (SFP) Clusters (primary)888
MemberOfViewView884CWE Cross-section
CWE Cross-section (primary)884
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
OWASP Top Ten 2004A9CWE More SpecificDenial of Service
CERT C Secure CodingFLP03-CDetect and handle floating point errors
CERT C Secure CodingINT33-CEnsure that division and modulo operations do not result in divide-by-zero errors
CERT Java Secure CodingNUM02-JEnsure that division and modulo operations do not result in divide-by-zero errors
CERT C++ Secure CodingINT33-CPPEnsure that division and modulo operations do not result in divide-by-zero errors
CERT C++ Secure CodingFLP03-CPPDetect and handle floating point errors
Software Fault PatternsSFP1Glitch in computation
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-07-01Sean EidemillerCigitalExternal
added/updated demonstrative examples
2008-07-01Eric DalciCigitalExternal
updated Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Common_Consequences, Description, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2009-05-27CWE Content TeamMITREInternal
updated Demonstrative_Examples
2009-10-29CWE Content TeamMITREInternal
updated Other_Notes
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-09-13CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2014-07-30CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITREInternal
updated Relationships

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Page Last Updated: January 18, 2017