CWE-537 Variante Incompleto

Java Runtime Error Message Containing Sensitive Information

This vulnerability occurs when a Java application's runtime error messages reveal sensitive details about the system, such as file paths, internal IP addresses, or stack traces. Attackers can…

Definição

What is CWE-537?

This vulnerability occurs when a Java application's runtime error messages reveal sensitive details about the system, such as file paths, internal IP addresses, or stack traces. Attackers can exploit these overly informative error messages to map the application's structure and gather intelligence for further attacks.
When an unhandled exception occurs, the default behavior in many Java applications is to display a detailed error message to the user. These messages often contain internal data like server file system paths, database connection strings, library versions, or configuration details. This information is invaluable to an attacker, as it helps them understand the underlying technology stack and pinpoint weaknesses without needing to probe the system directly. To prevent this, developers should implement a global exception handler that catches all unhandled exceptions and replaces verbose system-generated messages with generic, user-friendly ones. All detailed error information should be logged securely on the server side for debugging purposes, never exposed to the end-user. This practice, often called 'security through obscurity,' is a critical layer in a defense-in-depth strategy, ensuring that failures don't inadvertently hand attackers a roadmap to your system.
Impacto no mundo real

Real-world CVEs caused by CWE-537

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

    In the following Java example the class InputFileRead enables an input file to be read using a FileReader object. In the constructor of this class a default input file path is set to some directory on the local file system and the method setInputFile must be called to set the name of the input file to be read in the default directory. The method readInputFile will create the FileReader object and will read the contents of the file. If the method setInputFile is not called prior to calling the method readInputFile then the File object will remain null when initializing the FileReader object. A Java RuntimeException will be raised, and an error message will be output to the user.

  2. 2

    However, the error message output to the user contains information regarding the default directory on the local file system. This information can be exploited and may lead to unauthorized access or use of the system. Any Java RuntimeExceptions that are handled should not expose sensitive information to the user.

  3. 3

    In the example below, the BankManagerLoginServlet servlet class will process a login request to determine if a user is authorized to use the BankManager Web service. The doPost method will retrieve the username and password from the servlet request and will determine if the user is authorized. If the user is authorized the servlet will go to the successful login page. Otherwise, the servlet will raise a FailedLoginException and output the failed login message to the error page of the service.

  4. 4

    However, the output message generated by the FailedLoginException includes the user-supplied password. Even if the password is erroneous, it is probably close to the correct password. Since it is printed to the user's page, anybody who can see the screen display will be able to see the password. Also, if the page is cached, the password might be written to disk.

Exemplo de código vulnerável

Vulnerable Java

In the following Java example the class InputFileRead enables an input file to be read using a FileReader object. In the constructor of this class a default input file path is set to some directory on the local file system and the method setInputFile must be called to set the name of the input file to be read in the default directory. The method readInputFile will create the FileReader object and will read the contents of the file. If the method setInputFile is not called prior to calling the method readInputFile then the File object will remain null when initializing the FileReader object. A Java RuntimeException will be raised, and an error message will be output to the user.

Vulnerável Java 
public class InputFileRead {
  		private File readFile = null;
  		private FileReader reader = null;
  		private String inputFilePath = null;
  		private final String DEFAULT_FILE_PATH = "c:\\somedirectory\\";
  		public InputFileRead() {
  			inputFilePath = DEFAULT_FILE_PATH;
  		}
  		public void setInputFile(String inputFile) {
```
/* Assume appropriate validation / encoding is used and privileges / permissions are preserved */* 
  				}
  		
  		public void readInputFile() {
  		```
  				try {
  					reader = new FileReader(readFile);
  					...
  				} catch (RuntimeException rex) {
  					System.err.println("Error: Cannot open input file in the directory " + inputFilePath);
  					System.err.println("Input file has not been set, call setInputFile method before calling readInputFile");
  				} catch (FileNotFoundException ex) {...}
  		}
  }
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-537

  • Implementation Do not expose sensitive error information to the user.
Sinais de deteção

How to detect CWE-537

SAST High

Executar análise estática (SAST) na base de código à procura do padrão inseguro no fluxo de dados.

DAST Moderate

Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.

Runtime Moderate

Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.

Code review Moderate

Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-537 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-537?

This vulnerability occurs when a Java application's runtime error messages reveal sensitive details about the system, such as file paths, internal IP addresses, or stack traces. Attackers can exploit these overly informative error messages to map the application's structure and gather intelligence for further attacks.

Qual a gravidade do CWE-537?

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-537?

MITRE lists the following affected platforms: Java.

Como posso prevenir o CWE-537?

Do not expose sensitive error information to the user.

Como é que o Plexicus deteta e corrige o CWE-537?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-537 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-537?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/537.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-537

CWE-211 Pai

Externally-Generated Error Message Containing Sensitive Information

This vulnerability occurs when an application triggers an error message from an external component—like a database, interpreter, or…

CWE-535 Irmão

Exposure of Information Through Shell Error Message

This vulnerability occurs when a web application's command shell returns detailed error messages to users. Attackers can analyze these…

CWE-536 Irmão

Servlet Runtime Error Message Containing Sensitive Information

This vulnerability occurs when a Java servlet application displays detailed runtime error messages that reveal sensitive information about…

Recursos

Further reading

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