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 searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-547 Base Draft
Use of Hard-coded, Security-relevant Constants
This vulnerability occurs when code directly embeds security-critical values like passwords, cryptographic keys, or access levels as raw numbers or strings, instead of using named constants or…
Definition
What is CWE-547?
This vulnerability occurs when code directly embeds security-critical values like passwords, cryptographic keys, or access levels as raw numbers or strings, instead of using named constants or configuration files. This practice makes the code brittle and error-prone during updates or security reviews.
Hard-coding security values creates a maintenance nightmare. If a secret needs to be rotated or a permission level changed, developers must hunt through the entire codebase for every occurrence. Missing just one instance can introduce a security gap or break functionality. Once software is deployed, updating these embedded values often requires a full re-release, which may not even be possible in some environments.
These constants also risk exposure if the code is ever leaked or reverse-engineered, turning a simple configuration change into a major breach. While SAST tools can flag the pattern, Plexicus uses AI to not only detect these hard-coded secrets but also suggest the specific code fix—like moving the value to a secure configuration manager—saving hours of manual refactoring and reducing human error.
Real-world impact
Real-world CVEs caused by CWE-547
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
The usage of symbolic names instead of hard-coded constants is preferred.
- 2
The following is an example of using a hard-coded constant instead of a symbolic name.
- 3
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.
- 4
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.
Vulnerable code example
Vulnerable C
The following is an example of using a hard-coded constant instead of a symbolic name.
char buffer[1024];
...
fgets(buffer, 1024, stdin); Secure code example
Secure C
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.
enum { MAX_BUFFER_SIZE = 1024 };
...
char buffer[MAX_BUFFER_SIZE];
...
fgets(buffer, MAX_BUFFER_SIZE, stdin); What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-547
- Implementation Avoid using hard-coded constants. Configuration files offer a more flexible solution.
Detection signals
How to detect CWE-547
CWE-547
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Frequently asked questions What is CWE-547?
How serious is CWE-547?
What languages or platforms are affected by CWE-547?
How can I prevent CWE-547?
How does Plexicus detect and fix CWE-547?
Where can I learn more about CWE-547?
Frequently asked questions
What is CWE-547?
This vulnerability occurs when code directly embeds security-critical values like passwords, cryptographic keys, or access levels as raw numbers or strings, instead of using named constants or configuration files. This practice makes the code brittle and error-prone during updates or security reviews.
How serious is CWE-547?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-547?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-547?
Avoid using hard-coded constants. Configuration files offer a more flexible solution.
How does Plexicus detect and fix CWE-547?
Plexicus's SAST engine matches the data-flow signature for CWE-547 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-547?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/547.html. You can also reference OWASP and NIST documentation for adjacent guidance.
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