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
Scope
Effect
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.
More information is available — Please select a different filter.
Page Last Updated:
May 05, 2017
Use of the Common Weakness Enumeration and the associated references from this website are subject to the
Terms of Use. For more information, please email
cwe@mitre.org.
Description
