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.)
CWE-500 Variante Rascunho
Public Static Field Not Marked Final
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Definição
What is CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Public static fields act as global variables within your application's classloader. Because they are public, any other class can directly read and, crucially, modify their value without using proper getter or setter methods. This bypasses any validation, logging, or synchronization logic you might have in place, leading to unpredictable state changes that are difficult to trace and debug.
To prevent this, you should mark any necessary public static fields as `final` to make them constants. If a field truly needs to be mutable, consider making it private and providing controlled access through static methods, applying the principle of encapsulation even to static members to maintain data integrity and thread safety.
Impacto no mundo real
Real-world CVEs caused by CWE-500
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
Identificar um caminho de código que trata input não confiável sem validação.
- 2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
- 3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
- 4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.
Exemplo de código vulnerável
Vulnerable C++
The following examples use of a public static String variable to contain the name of a property/configuration file for the application.
class SomeAppClass {
public:
static string appPropertiesConfigFile = "app/properties.config";
...
} Exemplo de código seguro
Secure C++
Having a public static variable that is not marked final (constant) may allow the variable to the altered in a way not intended by the application. In this example the String variable can be modified to indicate a different on nonexistent properties file which could cause the application to crash or caused unexpected behavior.
class SomeAppClass {
public:
static const string appPropertiesConfigFile = "app/properties.config";
...
} 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-500
- Architecture and Design Clearly identify the scope for all critical data elements, including whether they should be regarded as static.
- Implementation Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
Sinais de deteção
How to detect CWE-500
CWE-500
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Perguntas frequentes O que é o CWE-500?
Qual a gravidade do CWE-500?
Que linguagens ou plataformas são afetadas pelo CWE-500?
Como posso prevenir o CWE-500?
Como é que o Plexicus deteta e corrige o CWE-500?
Onde posso saber mais sobre o CWE-500?
Frequently asked questions
O que é o CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Qual a gravidade do CWE-500?
A MITRE classifica a probabilidade de exploração como Alta — esta fraqueza é ativamente explorada em campo e deve ser priorizada para remediação.
Que linguagens ou plataformas são afetadas pelo CWE-500?
MITRE lists the following affected platforms: C++, Java.
Como posso prevenir o CWE-500?
Clearly identify the scope for all critical data elements, including whether they should be regarded as static. Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
Como é que o Plexicus deteta e corrige o CWE-500?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-500 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-500?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/500.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-500
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