CWE-377 Classe Incomplet

Insecure Temporary File

This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing attackers to read, modify, or delete sensitive data.

Définition

What is CWE-377?

This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing attackers to read, modify, or delete sensitive data.
Insecure temporary files are a common but dangerous flaw. They happen when developers use predictable filenames, place files in world-writable directories, or set overly permissive file access rights. Attackers can exploit this by 'symlinking' a predictable filename to a critical system file, performing a race condition to replace the file after creation, or simply reading the exposed data. This can lead to information disclosure, data corruption, or even a full system compromise. Preventing this requires using secure, random filenames, setting restrictive file permissions (like 0600), and leveraging secure system APIs designed for temporary file creation. Managing this at scale across numerous applications is difficult; an ASPM like Plexicus can help you track and remediate these flaws across your entire stack. While SAST tools catch the pattern, Plexicus uses AI to suggest the actual code fix, such as replacing insecure `tmpnam()` calls with secure `mkstemp()`, saving hours of manual work.
Impact réel

Real-world CVEs caused by CWE-377

  • CVE-2022-41954

    A library uses the Java File.createTempFile() method which creates a file with "-rw-r--r--" default permissions on Unix-like operating systems

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 C

The following code uses a temporary file for storing intermediate data gathered from the network before it is processed.

Vulnérable C 
if (tmpnam_r(filename)) {
  		FILE* tmp = fopen(filename,"wb+");
  		while((recv(sock,recvbuf,DATA_SIZE, 0) > 0)&(amt!=0)) amt = fwrite(recvbuf,1,DATA_SIZE,tmp);
  }
  ...
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-377

  • 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-377

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.)

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-377 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-377 ?

This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing attackers to read, modify, or delete sensitive data.

Quelle est la gravité de CWE-377 ?

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-377 ?

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-377 ?

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-377 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-377 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-377 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/377.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-377

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Ressources

Further reading

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