CWE-514 Class Incomplete

Covert Channel

A covert channel is a hidden communication path that allows data to be transmitted in a way that bypasses the system's intended security controls and monitoring.

Definition

What is CWE-514?

A covert channel is a hidden communication path that allows data to be transmitted in a way that bypasses the system's intended security controls and monitoring.
Covert channels work by exploiting legitimate system features—like timing, storage patterns, or resource usage—to secretly encode and transfer information. Attackers or malicious processes use these channels to exfiltrate data, coordinate actions, or maintain persistence without triggering standard security alerts, effectively hiding in plain sight. From a developer's perspective, these channels are dangerous because the system neither authorizes nor detects the unauthorized transmission. This lack of awareness means security tools focused on network traffic or file permissions may completely miss the leak, leaving sensitive data exposed through unexpected side channels in your own application logic or platform dependencies.
Real-world impact

Real-world CVEs caused by CWE-514

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

    In this example, the attacker observes how long an authentication takes when the user types in the correct password.

  2. 2

    When the attacker tries their own values, they can first try strings of various length. When they find a string of the right length, the computation will take a bit longer, because the for loop will run at least once. Additionally, with this code, the attacker can possibly learn one character of the password at a time, because when they guess the first character right, the computation will take longer than a wrong guesses. Such an attack can break even the most sophisticated password with a few hundred guesses.

  3. 3

    Note that in this example, the actual password must be handled in constant time as far as the attacker is concerned, even if the actual password is of an unusual length. This is one reason why it is good to use an algorithm that, among other things, stores a seeded cryptographic one-way hash of the password, then compare the hashes, which will always be of the same length.

Vulnerable code example

Vulnerable Python

When the attacker tries their own values, they can first try strings of various length. When they find a string of the right length, the computation will take a bit longer, because the for loop will run at least once. Additionally, with this code, the attacker can possibly learn one character of the password at a time, because when they guess the first character right, the computation will take longer than a wrong guesses. Such an attack can break even the most sophisticated password with a few hundred guesses.

Vulnerable Python 
def validate_password(actual_pw, typed_pw): 
  		if len(actual_pw) <> len(typed_pw): 
  			return 0
  		for i in len(actual_pw): 
  			if actual_pw[i] <> typed_pw[i]: 
  				return 0
  		return 1
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-514

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Detection signals

How to detect CWE-514

Architecture or Design Review SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Plexicus auto-fix

Plexicus auto-detects CWE-514 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-514?

A covert channel is a hidden communication path that allows data to be transmitted in a way that bypasses the system's intended security controls and monitoring.

How serious is CWE-514?

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-514?

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

How can I prevent CWE-514?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

How does Plexicus detect and fix CWE-514?

Plexicus's SAST engine matches the data-flow signature for CWE-514 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-514?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/514.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-514

CWE-1229 Parent

Creation of Emergent Resource

This vulnerability occurs when a system's normal operations unintentionally create new, exploitable resources that attackers can use to…

CWE-385 Child

Covert Timing Channel

A covert timing channel is a security flaw where an attacker can deduce secret information by observing how long certain operations take…

CWE-515 Child

Covert Storage Channel

A covert storage channel is a type of security flaw where one process secretly encodes data into a shared system resource (like a file,…

Resources

Further reading

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