CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
Home > CWE List > CWE- Individual Dictionary Definition (2.10)  
ID

CWE-547: Use of Hard-coded, Security-relevant Constants

Weakness ID: 547
Abstraction: Variant
Status: Draft
Presentation Filter:
+ Description

Description Summary

The program uses hard-coded constants instead of symbolic names for security-critical values, which increases the likelihood of mistakes during code maintenance or security policy change.

Extended Description

If the developer does not find all occurrences of the hard-coded constants, an incorrect policy decision may be made if one of the constants is not changed. Making changes to these values will require code changes that may be difficult or impossible once the system is released to the field. In addition, these hard-coded values may become available to attackers if the code is ever disclosed.

+ Time of Introduction
  • Implementation
+ Common Consequences
ScopeEffect
Other

Technical Impact: Varies by context; Quality degradation

The existence of hardcoded constants could cause unexpected behavior and the introduction of weaknesses during code maintenance or when making changes to the code if all occurrences are not modified. The use of hardcoded constants is an indication of poor quality.

+ Demonstrative Examples

Example 1

The usage of symbolic names instead of hard-coded constants is preferred.

The following is an example of using a hard-coded constant instead of a symbolic name.

(Bad Code)
Example Languages: C and C++ 
char buffer[1024];
...
fgets(buffer, 1024, stdin);

If the buffer value needs to be changed, then it has to be altered in more than one place. If the developer forgets or does not find all occurences, in this example it could lead to a buffer overflow.

(Bad Code)
Example Languages: C and C++ 
enum { MAX_BUFFER_SIZE = 1024 };
...
char buffer[MAX_BUFFER_SIZE];
...
fgets(buffer, MAX_BUFFER_SIZE, stdin);

In this example the developer will only need to change one value and all references to the buffer size are updated, as a symbolic name is used instead of a hard-coded constant.

+ Potential Mitigations

Phase: Implementation

Avoid using hard-coded constants. Configuration files offer a more flexible solution.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class398Indicator of Poor Code Quality
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory736CERT C Secure Coding Section 02 - Declarations and Initialization (DCL)
Weaknesses Addressed by the CERT C Secure Coding Standard (primary)734
ChildOfCategoryCategory950SFP Secondary Cluster: Hardcoded Sensitive Data
Software Fault Pattern (SFP) Clusters (primary)888
MemberOfViewView884CWE Cross-section
CWE Cross-section (primary)884
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
Anonymous Tool Vendor (under NDA)
CERT C Secure CodingDCL06-CUse meaningful symbolic constants to represent literal values in program logic
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
Anonymous Tool Vendor (under NDA)Externally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Description, Relationships, Taxonomy_Mappings
2008-11-24CWE Content TeamMITREInternal
updated Description, Potential_Mitigations, Relationships, Taxonomy_Mappings
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2011-06-27CWE Content TeamMITREInternal
updated Common_Consequences
2012-05-11CWE Content TeamMITREInternal
updated Common_Consequences, Relationships
2012-10-30CWE Content TeamMITREInternal
updated Potential_Mitigations
2014-07-30CWE Content TeamMITREInternal
updated Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Security-relevant Constants

More information is available — Please select a different filter.
Page Last Updated: January 11, 2017