CWE-276 Base Rascunho Medium likelihood

Incorrect Default Permissions

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,…

Definição

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.
Impacto no mundo real

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.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    Identificar um caminho de código que trata input não confiável sem validação.

  2. 2

    Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.

  3. 3

    Entregar o payload através de um pedido normal e observar a reação da aplicação.

  4. 4

    Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.

Exemplo de código vulnerável

Vulnerable pseudo

A MITRE não publicou um exemplo de código para este CWE. O padrão abaixo é ilustrativo — consulte os Recursos para referências canónicas.

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

Secure pseudo

Seguro 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.
Lista de verificação de prevenção

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.
Sinais de deteção

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

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-276 e abre um PR de correção em menos de 60 segundos.

O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.

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Perguntas frequentes

Frequently asked questions

O que é o 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.

Qual a gravidade do CWE-276?

A MITRE classifica a probabilidade de exploração como Média — a exploração é realista mas normalmente requer condições específicas.

Que linguagens ou plataformas são afetadas pelo CWE-276?

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

Como posso prevenir o 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…

Como é que o Plexicus deteta e corrige o CWE-276?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-276 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.

Onde posso saber mais sobre o CWE-276?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/276.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-276

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CWE-281 Irmão

Improper Preservation of Permissions

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Recursos

Further reading

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