CWE-276: Incorrect Default Permissions

Définition

What is CWE-276?

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of restricting write access to authorized users or processes, the installation allows unintended actors to modify, delete, or corrupt critical application files.

Incorrect default permissions are a common installation-time mistake where files and folders are created with global read/write access (e.g., world-writable). This often happens because the installer runs with elevated privileges but does not properly lock down the resources it deploys. The result is that any user or service on the system, including low-privilege accounts or malware, can alter configuration files, binaries, or libraries, leading to a direct path for privilege escalation, data tampering, or denial of service. To prevent this, developers and DevOps teams must ensure installation scripts explicitly set secure permissions, adhering to the principle of least privilege. Best practices include removing world-writable bits, assigning ownership to specific service accounts, and validating permissions post-deployment. Automated security scanning tools can also detect and flag overly permissive files as part of a continuous integration pipeline.

Impact réel

Real-world CVEs caused by CWE-276

CVE-2005-1941

Executables installed world-writable.
CVE-2002-1713

Home directories installed world-readable.
CVE-2001-1550

World-writable log files allow information loss; world-readable file has cleartext passwords.
CVE-2002-1711

World-readable directory.
CVE-2002-1844

Windows product uses insecure permissions when installing on Solaris (genesis: port error).
CVE-2001-0497

Insecure permissions for a shared secret key file. Overlaps cryptographic problem.
CVE-1999-0426

Default permissions of a device allow IP spoofing.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

1
Identifier un chemin de code qui traite des entrées non fiables sans validation.
2
Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.
3
Délivrer la charge utile via une requête normale et observer la réaction de l'application.
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 pseudo

MITRE n'a pas publié d'exemple de code pour ce CWE. Le motif ci-dessous est illustratif — voir Ressources pour les références canoniques.

Vulnérable pseudo

// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}

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-276

Architecture and Design / Operation The architecture needs to access and modification attributes for files to only those users who actually require those actions.
Architecture and Design Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Signaux de détection

How to detect CWE-276

Automated Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Inter-application Flow Analysis

Manual Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Automated Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria Web Application Scanner Web Services Scanner Database Scanners

Dynamic Analysis with Manual Results Interpretation High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Host Application Interface Scanner ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer Automated Monitored Execution Forced Path Execution

Manual Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Manual Source Code Review (not inspections) ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source

Automated Static Analysis - Source Code SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Context-configured Source Code Weakness Analyzer

CWE-276

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Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-276 ?

This vulnerability occurs when software installation scripts set overly permissive file or directory access rights by default. Instead of restricting write access to authorized users or processes, the installation allows unintended actors to modify, delete, or corrupt critical application files.

Quelle est la gravité de CWE-276 ?

MITRE évalue la probabilité d'exploitation comme Moyenne — l'exploitation est réaliste mais nécessite généralement des conditions spécifiques.

Quels langages ou plateformes sont affectés par CWE-276 ?

MITRE lists the following affected platforms: Not Technology-Specific, ICS/OT.

Comment puis-je prévenir CWE-276 ?

The architecture needs to access and modification attributes for files to only those users who actually require those actions. Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and…

Comment Plexicus détecte et corrige CWE-276 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-276 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-276 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/276.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-276

CWE-732 Parent

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Incorrect Default Permissions

What is CWE-276?

Real-world CVEs caused by CWE-276

Parcours de l'attaquant étape par étape

Vulnerable pseudo

Secure pseudo

How to prevent CWE-276

How to detect CWE-276

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

Frequently asked questions

Weaknesses related to CWE-276

Incorrect Permission Assignment for Critical Resource

Sensitive Cookie Without 'HttpOnly' Flag

Insecure Inherited Permissions

Insecure Preserved Inherited Permissions

Incorrect Execution-Assigned Permissions

Improper Preservation of Permissions

Critical Data Element Declared Public

Further reading

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Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`