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

Description

The product 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.

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.

Potential Impact

Other

Varies by Context, Quality Degradation, Reduce Maintainability

Demonstrative Examples

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

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 occurrences, in this example it could lead to a buffer overflow.

Good

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.

Mitigations & Prevention

Implementation

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

Detection Methods

Automated Static Analysis High — Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then sea

Taxonomy Mappings

CERT C Secure Coding: DCL06-C — Use meaningful symbolic constants to represent literal values in program logic

Frequently Asked Questions

What is CWE-547?

CWE-547 (Use of Hard-coded, Security-relevant Constants) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Base-level weakness. The product 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.

How can CWE-547 be exploited?

Attackers can exploit CWE-547 (Use of Hard-coded, Security-relevant Constants) to varies by context, quality degradation, reduce maintainability. This weakness is typically introduced during the Implementation phase of software development.

How do I prevent CWE-547?

Key mitigations include: Avoid using hard-coded constants. Configuration files offer a more flexible solution.

What is the severity of CWE-547?

CWE-547 is classified as a Base-level weakness (Medium abstraction). Its actual severity depends on the specific context and how the weakness manifests in your application.