CWE-515: Covert Storage Channel

BaseIncompleteExploit Likelihood: High

A covert storage channel transfers information through the setting of bits by one program and the reading of those bits by another. What distinguishes this case from that of ordinary operation is that the bits are used to convey encoded information.

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Extended Description

Covert storage channels occur when out-of-band data is stored in messages for the purpose of memory reuse. Covert channels are frequently classified as either storage or timing channels. Examples would include using a file intended to hold only audit information to convey user passwords--using the name of a file or perhaps status bits associated with it that can be read by all users to signal the contents of the file. Steganography, concealing information in such a manner that no one but the intended recipient knows of the existence of the message, is a good example of a covert storage channel.

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-515 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-515, Covert Storage Channel, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Covert Storage Channel during Implementation

MITRE associates mitigation with Implementation; recorded impacts include Read Application Data; related weaknesses include CWE-514. Use these source-defined anchors to turn CWE-515 into implementation, review, and verification checks for the affected component.

CWE-515: Covert Storage Channel — MITRE CWE

Triage CWE-515 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-515, Covert Storage Channel, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-515

Apply MITRE's full root-cause mapping guidance when using CWE-515, Covert Storage Channel. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-515 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-515, Covert Storage Channel. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-515: Covert Storage Channel?+

CWE-515: Covert Storage Channel is a Common Weakness Enumeration (CWE) entry maintained by MITRE. A covert storage channel transfers information through the setting of bits by one program and the reading of those bits by another. What distinguishes this case from that of ordinary operation is that the bits are used to convey encoded information. Covert storage channels occur when out-of-band data is stored in messages for the purpose of memory reuse. Covert channels are frequently classified as either storage or timing channels. Examples would include using a file intended to hold only audit information to convey user passwords--using the name of a file or perhaps status bits associated with it that can be read by all users to signal the contents of the file. Steganography, concealing information in such a manner that no one but the intended recipient knows of the existence of the message, is a good example of a covert storage channel.

What are the security consequences of Covert Storage Channel?+

If exploited, CWE-515 (Covert Storage Channel) it can compromise Confidentiality and Integrity, leading to outcomes such as Read Application Data.

How do you prevent or mitigate Covert Storage Channel?+

Recommended mitigations for CWE-515 include: Ensure that all reserved fields are set to zero before messages are sent and that no unnecessary information is included.

Which programming languages are affected by Covert Storage Channel?+

CWE-515 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-515 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-515: Covert Storage Channel

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