Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-347 Base Draft
Improper Verification of Cryptographic Signature
This vulnerability occurs when an application fails to properly check the digital signature on data, or skips the verification step entirely, allowing tampered or forged information to be accepted…
Definition
What is CWE-347?
This vulnerability occurs when an application fails to properly check the digital signature on data, or skips the verification step entirely, allowing tampered or forged information to be accepted as legitimate.
Cryptographic signatures are essential for verifying the authenticity and integrity of data, such as software updates, authentication tokens, or API messages. When an application doesn't validate these signatures correctly—by using the wrong key, ignoring expiration, or not checking the result—attackers can inject malicious data, escalate privileges, or bypass security controls. This often happens due to misunderstood libraries, manual implementation of complex protocols, or simply overlooking the verification step after signature extraction.
Detecting these flaws requires checking code paths where signatures are processed, ensuring robust key management, and using up-to-date libraries. While SAST tools can flag missing verification calls, managing this at scale across microservices and third-party dependencies is challenging. An ASPM like Plexicus helps by correlating these findings across your entire stack, and its AI can provide automated, context-aware remediation suggestions to fix the vulnerable code efficiently.
Real-world impact
Real-world CVEs caused by CWE-347
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Does not properly verify signatures for "trusted" entities.
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Insufficient verification allows spoofing.
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Insufficient verification allows spoofing.
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Accepts a configuration file without a Message Integrity Check (MIC) signature.
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 Java
In the following code, a JarFile object is created from a downloaded file.
File f = new File(downloadedFilePath);
JarFile jf = new JarFile(f); 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-347
- 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-347
Plexicus auto-detects CWE-347 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.
Frequently asked questions What is CWE-347?
How serious is CWE-347?
What languages or platforms are affected by CWE-347?
How can I prevent CWE-347?
How does Plexicus detect and fix CWE-347?
Where can I learn more about CWE-347?
Frequently asked questions
What is CWE-347?
This vulnerability occurs when an application fails to properly check the digital signature on data, or skips the verification step entirely, allowing tampered or forged information to be accepted as legitimate.
How serious is CWE-347?
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-347?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-347?
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-347?
Plexicus's SAST engine matches the data-flow signature for CWE-347 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-347?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/347.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-347
CWE-345 Parent
Insufficient Verification of Data Authenticity
This vulnerability occurs when an application fails to properly check where data comes from or confirm its legitimacy, allowing untrusted…
CWE-1293 Sibling
Missing Source Correlation of Multiple Independent Data
This vulnerability occurs when a system trusts a single source of data without verification, making it impossible to detect if that source…
CWE-346 Sibling
Origin Validation Error
This vulnerability occurs when an application fails to properly confirm the true origin of incoming data or communication, allowing…
CWE-348 Sibling
Use of Less Trusted Source
This vulnerability occurs when a system has access to multiple sources for the same critical data, but it chooses to rely on the less…
CWE-349 Sibling
Acceptance of Extraneous Untrusted Data With Trusted Data
This vulnerability occurs when a system processes both trusted and untrusted data together, but fails to separate them. The application…
CWE-351 Sibling
Insufficient Type Distinction
This vulnerability occurs when an application fails to properly differentiate between different types of data or objects, leading to…
CWE-352 Sibling
Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) happens when a web application cannot reliably tell if a user actually intended to submit a request,…
CWE-353 Sibling
Missing Support for Integrity Check
This vulnerability occurs when a system uses a communication protocol that lacks built-in integrity verification, such as a checksum or…
CWE-354 Sibling
Improper Validation of Integrity Check Value
This vulnerability occurs when software fails to properly check the integrity of data by validating its checksum or hash value. Without…
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