CWE-397: Declaration of Throws for Generic Exception

What is Declaration of Throws for Generic Exception?

• Overview: Declaration of Throws for Generic Exception is a vulnerability where a method in a programming language like Java is declared to throw a broad, generic exception type such as Exception or Throwable. This can obscure specific error details from developers, making it harder to handle errors effectively and appropriately.

• Exploitation Methods:

• Attackers can exploit this vulnerability by triggering generic exceptions to mask specific errors that could otherwise be detected and handled.
• Common attack patterns include forcing the application into an error state where more specific exception handling would prevent broader application failures.

• Security Impact:

• Direct consequences include the inability to handle specific errors properly, leading to unexpected application behavior or failures.
• Potential cascading effects involve masking critical application errors, making debugging and maintenance more challenging.
• Business impact can include increased downtime, higher maintenance costs, and potential data integrity issues if errors are not handled correctly.

• Prevention Guidelines:

• Specific code-level fixes include declaring methods to throw more specific exceptions rather than general ones like Exception or Throwable.
• Security best practices involve using language-specific exception hierarchies to anticipate and handle errors appropriately.
• Recommended tools and frameworks include static analysis tools that can detect broad exception declarations and suggest more specific alternatives.

Corgea can automatically detect and fix Declaration of Throws for Generic Exception in your codebase. Try Corgea free today.

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: C++, C#, Java, Python

Affected Technologies: Not specified

Vulnerable Code Example

C++ Example

#include <iostream>
#include <exception>
#include <stdexcept>

// Function demonstrating the vulnerability
void processFile(const std::string& filename) throw(std::exception) { // {6}
    // This function declares that it throws a generic std::exception
    if (filename.empty()) {
        throw std::invalid_argument("Filename cannot be empty"); // Specific exception
    }
    // Simulate file processing
    // Potentially other specific exceptions can be thrown
    std::cout << "Processing file: " << filename << std::endl;
}

int main() {
    try {
        processFile("");
    } catch (std::exception& e) { // {10}
        // Catching a generic exception can hide specific issues
        std::cerr << "Error: " << e.what() << std::endl;
    }
    return 0;
}

Explanation of Vulnerability

• Line {6}: The function processFile declares it might throw a generic std::exception, which is too broad and does not convey the specific errors that might occur.
• Line {10}: The catch block catches a generic exception, which can obscure the nature of the error and make debugging difficult.

How to fix Declaration of Throws for Generic Exception?

To fix this vulnerability, you should:

1. Specify Exceptions: Use specific exception types in the throw declaration to make it clear what errors can occur.
2. Specific Catch Blocks: Catch specific exceptions instead of a generic one to handle different errors appropriately.
3. Documentation: Document the specific exceptions that a function might throw to aid developers in understanding the possible error conditions.

Fixed Code Example

#include <iostream>
#include <stdexcept>

// Function with specific exception declarations
void processFile(const std::string& filename) throw(std::invalid_argument, std::runtime_error) { // {6}
    if (filename.empty()) {
        throw std::invalid_argument("Filename cannot be empty");
    }
    // Simulate file processing
    std::cout << "Processing file: " << filename << std::endl;
}

int main() {
    try {
        processFile("");
    } catch (const std::invalid_argument& e) { // {11}
        // Specific handling for invalid arguments
        std::cerr << "Invalid Argument Error: " << e.what() << std::endl;
    } catch (const std::runtime_error& e) { // {14}
        // Specific handling for runtime errors
        std::cerr << "Runtime Error: " << e.what() << std::endl;
    } catch (const std::exception& e) { // {18}
        // Fallback for any other std exceptions
        std::cerr << "General Error: " << e.what() << std::endl;
    }
    return 0;
}

Explanation of Fixes

• Line {6}: The throw list now includes specific exceptions (std::invalid_argument, std::runtime_error), making it clear what specific errors the function might produce.
• Lines {11-18}: The catch blocks are now designed to handle specific exceptions, which allows for more precise error handling and debugging. A fallback catch block for std::exception is included to handle any unforeseen exceptions safely.

This improved formatting and explanation ensure that the examples are clear, realistic, and follow C++ best practices.