CWE-378 Base Brouillon High likelihood

Creation of Temporary File With Insecure Permissions

This vulnerability occurs when a program creates a temporary file but sets its file permissions too loosely, allowing other users or processes on the system to read, modify, or delete the file.

Définition

What is CWE-378?

This vulnerability occurs when a program creates a temporary file but sets its file permissions too loosely, allowing other users or processes on the system to read, modify, or delete the file.
When a temporary file is created with insecure permissions (like world-readable or world-writable), it becomes an easy target for attackers on the same system. They can directly read sensitive data from the file, inject malicious content into it, or even delete it to cause a denial of service. This is especially dangerous because developers often assume temporary files are private and secure, leading them to store sensitive information like session tokens, passwords, or configuration data in them. To prevent this, always use secure APIs designed for temporary file creation that enforce strict permissions by default, such as `mkstemp` on Unix-like systems. If you must use a lower-level function, explicitly set restrictive file permissions immediately after creation. Additionally, consider using alternative, more secure storage methods like memory-based structures for highly sensitive data, and ensure proper file cleanup to reduce the attack window.
Impact réel

Real-world CVEs caused by CWE-378

  • CVE-2022-24823

    A network application framework uses the Java function createTempFile(), which will create a file that is readable by other local users of the system

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    In the following code examples a temporary file is created and written to. After using the temporary file, the file is closed and deleted from the file system.

  2. 2

    However, within this C/C++ code the method tmpfile() is used to create and open the temp file. The tmpfile() method works the same way as the fopen() method would with read/write permission, allowing attackers to read potentially sensitive information contained in the temp file or modify the contents of the file.

  3. 3

    Similarly, the createTempFile() method used in the Java code creates a temp file that may be readable and writable to all users.

  4. 4

    Additionally both methods used above place the file into a default directory. On UNIX systems the default directory is usually "/tmp" or "/var/tmp" and on Windows systems the default directory is usually "C:\\Windows\\Temp", which may be easily accessible to attackers, possibly enabling them to read and modify the contents of the temp file.

Exemple de code vulnérable

Vulnerable C

In the following code examples a temporary file is created and written to. After using the temporary file, the file is closed and deleted from the file system.

Vulnérable C 
FILE *stream;
  if( (stream = tmpfile()) == NULL ) {
  		perror("Could not open new temporary file\n");
  		return (-1);
  }
```
// write data to tmp file* 
  ...
  // remove tmp file
  rmtmp();
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-378

  • Requirements Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible.
  • Implementation Ensure that you use proper file permissions. This can be achieved by using a safe temp file function. Temporary files should be writable and readable only by the process that owns the file.
  • Implementation Randomize temporary file names. This can also be achieved by using a safe temp-file function. This will ensure that temporary files will not be created in predictable places.
Signaux de détection

How to detect CWE-378

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-378 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-378 ?

This vulnerability occurs when a program creates a temporary file but sets its file permissions too loosely, allowing other users or processes on the system to read, modify, or delete the file.

Quelle est la gravité de CWE-378 ?

MITRE évalue la probabilité d'exploitation comme Élevée — cette faiblesse est activement exploitée et doit être priorisée pour la remédiation.

Quels langages ou plateformes sont affectés par CWE-378 ?

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-378 ?

Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible. Ensure that you use proper file permissions. This can be achieved by using a safe temp file function. Temporary files should be writable and readable only by the process that owns the file.

Comment Plexicus détecte et corrige CWE-378 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-378 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-378 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/378.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-378

CWE-377 Parent

Insecure Temporary File

This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing…

CWE-379 Frère

Creation of Temporary File in Directory with Insecure Permissions

This vulnerability occurs when an application creates a temporary file in a directory that is too permissive, allowing unauthorized users…

Ressources

Further reading

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