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NonMember methods of non-final classes containing methods that perform security checks can be compromised if when a malicious subclass overrides the methods and omits the checks. For this reasonConsequently, these such methods must be declared private or final to prevent them from being extendedoverriding.

Noncompliant Code Example

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public void readSensitiveFile() {
  try {
    SecurityManager sm = System.getSecurityManager();
    if (sm != null) {  // Check iffor filepermission canto beread readfile
      sm.checkRead("/temp/tempFile");
    } 
    // Access the file
  } catch (SecurityException se) { 
    // Log exception  
  }
}

Compliant Solution

This compliant solution prohibits inheritance prevents overriding of the readSensitiveFile() method by declaring it as final.

public final void readSensitiveFile() {
  try {
    SecurityManager sm = System.getSecurityManager();
    if (sm != null) {  // checkCheck iffor filepermission canto beread readfile
      sm.checkRead("/temp/tempFile");
    } 
    // Access the file
  } catch (SecurityException se) { 
    // Log exception 
  }
}

Compliant Solution

This compliant solution prohibits inheritance prevents overriding of the readSensitiveFile() method by declaring it private.

private void readSensitiveFile() {
  try {
    SecurityManager sm = System.getSecurityManager();
    if (sm != null) {  // checkCheck iffor filepermission canto beread readfile
      sm.checkRead("/temp/tempFile");
    } 
    // Access the file
  } catch (SecurityException se) { 
    // Log exception 
  }
}

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MET03-EX0: Classes that are declared final are exempt from this guideline as they imply that the contained because their member methods cannot be overridden.

Risk Assessment

Failing Failure to declare a non-final class's method private or final can allow a affords the opportunity for a malicious subclass to circumvent bypass the security checks performed in the methods.

Automated Detection

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Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this guideline on the CERT website.

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