CWE-537 Variant Incomplete

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…

Definition

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.

Auswirkungen in der Praxis

Real-world CVEs caused by CWE-537

Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

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
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
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
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.

Verwundbares Codebeispiel

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.

Verwundbar 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) {...}
  		}
  }

Sicheres Codebeispiel

Secure pseudo

Sicher 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.

Präventions-Checkliste

How to prevent CWE-537

Implementation Do not expose sensitive error information to the user.

Erkennungssignale

How to detect CWE-537

SAST High

Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.

DAST Moderate

Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.

Runtime Moderate

Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.

Code review Moderate

Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.

Plexicus Auto-Fix

Plexicus erkennt CWE-537 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen

Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-537?

Wie gravierend ist CWE-537?

MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.

Welche Sprachen oder Plattformen sind von CWE-537 betroffen?

MITRE lists the following affected platforms: Java.

Wie kann ich CWE-537 verhindern?

Do not expose sensitive error information to the user.

Wie erkennt und behebt Plexicus CWE-537?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-537 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-537?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/537.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-537

CWE-211 Parent

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 Sibling

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 Sibling

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…

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