Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-13 Variant Draft
ASP.NET Misconfiguration: Password in Configuration File
This vulnerability occurs when an ASP.NET application stores passwords or other sensitive credentials in plaintext within configuration files like web.config. This exposes those credentials to…
Definition
What is CWE-13?
This vulnerability occurs when an ASP.NET application stores passwords or other sensitive credentials in plaintext within configuration files like web.config. This exposes those credentials to anyone with file system access, effectively bypassing security controls and granting unauthorized access to protected resources.
Configuration files such as web.config are often deployed alongside application code and may be readable by various system accounts or, in worst-case scenarios, accessible via web server misconfigurations. Storing secrets like database passwords, API keys, or service account credentials in these files creates a single point of failure. Attackers who can read the file—whether through directory traversal, compromised backups, or insider access—immediately gain the privileges associated with those credentials.
To prevent this, never store sensitive values in plaintext within configuration files. Instead, use secure alternatives like the ASP.NET built-in mechanisms for protecting configuration sections (e.g., `aspnet_regiis`), the Protected Configuration feature with RSA or DPAPI, or dedicated secret management services such as Azure Key Vault or HashiCorp Vault. For connection strings, consider using Integrated Windows Authentication where possible to eliminate password storage entirely.
Real-world impact
Real-world CVEs caused by CWE-13
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 4
Iterate until the response leaks data, executes attacker code, or escalates privileges.
Vulnerable code example
Vulnerable ASP.NET
The following example shows a portion of a configuration file for an ASP.Net application. This configuration file includes username and password information for a connection to a database, but the pair is stored in plaintext.
...
<connectionStrings>
<add name="ud_DEV" connectionString="connectDB=uDB; uid=db2admin; pwd=password; dbalias=uDB;" providerName="System.Data.Odbc" />
</connectionStrings>
... Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} 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-13
- Implementation Credentials stored in configuration files should be encrypted, Use standard APIs and industry accepted algorithms to encrypt the credentials stored in configuration files.
Detection signals
How to detect CWE-13
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
CWE-13
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-13?
How serious is CWE-13?
What languages or platforms are affected by CWE-13?
How can I prevent CWE-13?
How does Plexicus detect and fix CWE-13?
Where can I learn more about CWE-13?
Frequently asked questions
What is CWE-13?
This vulnerability occurs when an ASP.NET application stores passwords or other sensitive credentials in plaintext within configuration files like web.config. This exposes those credentials to anyone with file system access, effectively bypassing security controls and granting unauthorized access to protected resources.
How serious is CWE-13?
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-13?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-13?
Credentials stored in configuration files should be encrypted, Use standard APIs and industry accepted algorithms to encrypt the credentials stored in configuration files.
How does Plexicus detect and fix CWE-13?
Plexicus's SAST engine matches the data-flow signature for CWE-13 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-13?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/13.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-13
CWE-260 Parent
Password in Configuration File
This vulnerability occurs when an application stores sensitive passwords directly within a configuration file, making them easily readable…
CWE-258 Sibling
Empty Password in Configuration File
This vulnerability occurs when a configuration file, script, or application uses an empty string as a password, effectively disabling…
CWE-555 Sibling
J2EE Misconfiguration: Plaintext Password in Configuration File
A J2EE application insecurely stores an unprotected password within a configuration file.
Resources
Further reading
- MITRE — official CWE-13 https://cwe.mitre.org/data/definitions/13.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- How To: Encrypt Configuration Sections in ASP.NET 2.0 Using DPAPI https://learn.microsoft.com/en-us/previous-versions/msp-n-p/ff647398(v=pandp.10)?redirectedfrom=MSDN
- How To: Encrypt Configuration Sections in ASP.NET 2.0 Using RSA https://learn.microsoft.com/en-us/previous-versions/msp-n-p/ff650304(v=pandp.10)?redirectedfrom=MSDN
- .NET Framework Developer's Guide - Securing Connection Strings http://msdn.microsoft.com/en-us/library/89211k9b(VS.80).aspx
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