CWE-347 Base Brouillon

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…

Définition

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.
Vulnerability Diagram CWE-347
Improper Signature Verification JWT { "alg":"none" } { "user":"admin" } .<empty signature> # attacker forged Server (vulnerable) jwt.decode(token) # no verify=True trusts payload role=admin accepted Privilege escalation Server reads the JWT payload but skips signature verification.
Impact réel

Real-world CVEs caused by CWE-347

  • Does not properly verify signatures for "trusted" entities.

  • Insufficient verification allows spoofing.

  • Insufficient verification allows spoofing.

  • Accepts a configuration file without a Message Integrity Check (MIC) signature.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    Identifier un chemin de code qui traite des entrées non fiables sans validation.

  2. 2

    Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.

  3. 3

    Délivrer la charge utile via une requête normale et observer la réaction de l'application.

  4. 4

    Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.

Exemple de code vulnérable

Vulnerable Java

In the following code, a JarFile object is created from a downloaded file.

Vulnérable Java
File f = new File(downloadedFilePath);
  JarFile jf = new JarFile(f);
Exemple de code sécurisé

Secure pseudo

Sécurisé 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.
Liste de contrôle de prévention

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.
Signaux de détection

How to detect CWE-347

Automated Static Analysis High

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

Don't catalog this weakness. Prove it's reachable.

Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.

Questions fréquentes

Frequently asked questions

Qu'est-ce que 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.

Quelle est la gravité de CWE-347 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-347 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir 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.

Comment Plexicus détecte et corrige CWE-347 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-347 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-347 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/347.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

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 Frère

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 Frère

Origin Validation Error

This vulnerability occurs when an application fails to properly confirm the true origin of incoming data or communication, allowing…

CWE-348 Frère

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 Frère

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 Frère

Insufficient Type Distinction

This vulnerability occurs when an application fails to properly differentiate between different types of data or objects, leading to…

CWE-352 Frère

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 Frère

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 Frère

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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SAMPLE HANDOVER · ILLUSTRATIVE

Sample evidence handover

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VALIDATED FINDING Evidence attached

Server-Side Request Forgery in webhooks/receiver

demo-project/sample-app · src/webhooks/receiver.py:42

SeverityHigh CVSS 3.18.6 Priority79 Confirmedvia replay

Untrusted caller-supplied URLs reach an internal egress without an allowlist. Replayed in a sandbox against a fresh authorized target — the same control was validated to fail twice.

REVIEWER-READY REMEDIATION Merge-ready PR

Validate the target URL against an allowlist of permitted hostnames. Reject private/internal IP ranges. Enforce HTTPS only.

plexicus/remediation/webhooks-ssrf 3 changed · 0 new files
42resp = requests.get(target_url)
42+if not is_allowed_host(target_url):
43+  raise WebhookRejected(target_url)
44+resp = requests.get(target_url, timeout=5)
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  • Validated findings list
  • Merge-ready PRs
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