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Common Weakness Enumeration

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Home > CWE List > CWE-514: Covert Channel (4.18)
ID
CWE Glossary Definition

CWE-514: Covert Channel

Weakness ID: 514
Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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Description
A covert channel is a path that can be used to transfer information in a way not intended by the system's designers.
Extended Description
Typically the system has not given authorization for the transmission and has no knowledge of its occurrence.
Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Impact Details

Read Application Data; Bypass Protection Mechanism

Scope: Confidentiality, Access Control

Relationships
Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (View-1000)
Nature Type ID Name
ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 1229 Creation of Emergent Resource
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 385 Covert Timing Channel
ParentOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 515 Covert Storage Channel
CanFollow Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 205 Observable Behavioral Discrepancy
Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase Note
Implementation
Operation
Demonstrative Examples

Example 1


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

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.

(bad code)
Example Language: 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

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.



Detection Methods
Method Details

Architecture or Design Review

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.)

Effectiveness: SOAR Partial
Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature Type ID Name
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 968 SFP Secondary Cluster: Covert Channel
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1415 Comprehensive Categorization: Resource Control
Vulnerability Mapping Notes
Usage ALLOWED-WITH-REVIEW
(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason Abstraction

Rationale

This CWE entry is a Class and might have Base-level children that would be more appropriate

Comments

Examine children of this entry to see if there is a better fit
Notes

Theoretical

A covert channel can be thought of as an emergent resource, meaning that it was not an originally intended resource, however it exists due the application's behaviors.

Maintenance

As of CWE 4.9, members of the CWE Hardware SIG are working to improve CWE's coverage of transient execution weaknesses, which include issues related to Spectre, Meltdown, and other attacks that create or exploit covert channels. As a result of that work, this entry might change in CWE 4.10.
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
Landwehr Covert Channel
References
[REF-1431] Carl E. Landwehr, Alan R. Bull, John P. McDermott and William S. Choi. "A Taxonomy of Computer Program Security Flaws, with Examples". 1993年11月19日.
<https://cwe.mitre.org/documents/sources/ATaxonomyofComputerProgramSecurityFlawswithExamples%5BLandwehr93%5D.pdf>. (URL validated: 2024年11月17日)
[REF-1479] Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler and Rama S. Moorthy. "State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation". 2014-07.
<https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx>. (URL validated: 2025年09月05日)
Content History
Submissions
Submission Date Submitter Organization
2006年07月19日
(CWE Draft 3, 2006年07月19日) 		Landwehr
Modifications
Modification Date Modifier Organization
2025年09月09日
(CWE 4.18, 2025年09月09日) 		CWE Content Team MITRE
updated Detection_Factors, References
2024年07月16日
(CWE 4.15, 2024年07月16日) 		CWE Content Team MITRE
updated References
2024年02月29日
(CWE 4.14, 2024年02月29日) 		CWE Content Team MITRE
updated Demonstrative_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Relationships
2022年10月13日 CWE Content Team MITRE
updated Maintenance_Notes
2020年02月24日 CWE Content Team MITRE
updated Relationships
2017年11月08日 CWE Content Team MITRE
updated Relationships
2014年07月30日 CWE Content Team MITRE
updated Detection_Factors, Relationships
2014年06月23日 CWE Content Team MITRE
updated Related_Attack_Patterns
2013年02月21日 CWE Content Team MITRE
updated Description, Relationships, Theoretical_Notes
2012年05月11日 CWE Content Team MITRE
updated Related_Attack_Patterns, Relationships
2011年06月01日 CWE Content Team MITRE
updated Common_Consequences
2010年04月05日 CWE Content Team MITRE
updated Related_Attack_Patterns
2009年07月27日 CWE Content Team MITRE
updated Relationships
2008年10月14日 CWE Content Team MITRE
updated Description, Other_Notes, Theoretical_Notes
2008年09月08日 CWE Content Team MITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2008年07月01日 Eric Dalci Cigital
updated Time_of_Introduction
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Page Last Updated: September 09, 2025

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