CWE-272 Base Incompleto

Least Privilege Violation

This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.

Definição

What is CWE-272?

This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.
Many critical system functions, like changing the root directory with `chroot()`, require temporary high-level privileges. The secure pattern is to request these elevated rights, perform the single specific task, and then immediately and deliberately drop back down to a normal, restricted privilege level. Failing to do this creates a prolonged attack window where any subsequent bug or compromise in the software can be exploited with those high privileges, leading to severe system damage. For developers, this means your code should follow a 'need-to-know' and 'need-to-use' principle for permissions. Structure your program to operate with the least privilege possible by default, escalate only for discrete operations, and revert immediately. This practice, often called privilege dropping or shedding, is a core defense-in-depth strategy that limits the potential impact of other security flaws in your application.
Impacto no mundo real

Real-world CVEs caused by CWE-272

Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    The following example demonstrates the weakness.

  2. 2

    The following example demonstrates the weakness.

  3. 3

    The following code calls chroot() to restrict the application to a subset of the filesystem below APP_HOME in order to prevent an attacker from using the program to gain unauthorized access to files located elsewhere. The code then opens a file specified by the user and processes the contents of the file.

  4. 4

    Constraining the process inside the application's home directory before opening any files is a valuable security measure. However, the absence of a call to setuid() with some non-zero value means the application is continuing to operate with unnecessary root privileges. Any successful exploit carried out by an attacker against the application can now result in a privilege escalation attack because any malicious operations will be performed with the privileges of the superuser. If the application drops to the privilege level of a non-root user, the potential for damage is substantially reduced.

Exemplo de código vulnerável

Vulnerable C

The following example demonstrates the weakness.

Vulnerável C 
setuid(0);
```
// Do some important stuff* 
  setuid(old_uid);
  
   *// Do some non privileged stuff.*
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-272

  • Architecture and Design / Operation Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Architecture and Design Follow the principle of least privilege when assigning access rights to entities in a software system.
  • 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-272

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: ``` Compare binary / bytecode to application permission manifest

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

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: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Automated Static Analysis SOAR Partial

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

Architecture or Design Review High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Attack Modeling

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-272 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-272?

This vulnerability occurs when software fails to reduce its elevated system privileges after completing a sensitive operation, leaving it with unnecessary and dangerous access rights.

Qual a gravidade do CWE-272?

A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.

Que linguagens ou plataformas são afetadas pelo CWE-272?

A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.

Como posso prevenir o CWE-272?

Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software. Follow the principle of least privilege when assigning access rights to entities in a software system.

Como é que o Plexicus deteta e corrige o CWE-272?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-272 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-272?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/272.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-272

CWE-271 Pai

Privilege Dropping / Lowering Errors

This vulnerability occurs when a system or process fails to reduce its elevated permissions before transferring control of a resource to a…

CWE-273 Irmão

Improper Check for Dropped Privileges

This vulnerability occurs when an application tries to lower its system privileges but fails to verify that the operation was successful.

Recursos

Further reading

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