CWE-556 Variant Incomplete

ASP.NET Misconfiguration: Use of Identity Impersonation

This vulnerability occurs when an ASP.NET application is configured to run using impersonated credentials, which can grant the application excessive and unnecessary system privileges.

Definition

What is CWE-556?

This vulnerability occurs when an ASP.NET application is configured to run using impersonated credentials, which can grant the application excessive and unnecessary system privileges.
ASP.NET's identity impersonation feature allows an application to execute code using the security permissions of the requesting user or a specific account defined in its configuration. While this can be useful for delegated access, it often results in the application running with far higher privileges than it needs to perform its core functions, violating the principle of least privilege. This creates a significant security risk because if the application is compromised, an attacker inherits these elevated privileges. This can lead to unauthorized access to files, databases, or other system resources that should be off-limits, dramatically increasing the potential impact of a breach.
Real-world impact

Real-world CVEs caused by CWE-556

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

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-556

  • Architecture and Design Use the least privilege principle.
Detection signals

How to detect CWE-556

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

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Frequently asked questions

Frequently asked questions

What is CWE-556?

This vulnerability occurs when an ASP.NET application is configured to run using impersonated credentials, which can grant the application excessive and unnecessary system privileges.

How serious is CWE-556?

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-556?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-556?

Use the least privilege principle.

How does Plexicus detect and fix CWE-556?

Plexicus's SAST engine matches the data-flow signature for CWE-556 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-556?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/556.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-556

CWE-266 Parent

Incorrect Privilege Assignment

This vulnerability occurs when a system mistakenly grants a user, process, or entity a specific permission or privilege they should not…

CWE-1022 Sibling

Use of Web Link to Untrusted Target with window.opener Access

This vulnerability occurs when a web application links to an external, untrusted site without protecting its own window from being…

CWE-520 Sibling

.NET Misconfiguration: Use of Impersonation

This vulnerability occurs when a .NET application is configured to run with impersonation, potentially granting it excessive system-level…

CWE-9 Sibling

J2EE Misconfiguration: Weak Access Permissions for EJB Methods

This vulnerability occurs when Enterprise JavaBean (EJB) methods are configured with overly permissive access rights, allowing attackers…

Resources

Further reading

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