CWE-941: Incorrectly Specified Destination in a Communication Channel

What is Incorrectly Specified Destination in a Communication Channel?

• Overview: Incorrectly Specified Destination in a Communication Channel (CWE-941) occurs when a product creates a communication channel for an outgoing request but fails to specify the correct intended destination, leading to communication with an unintended or malicious actor.

• Exploitation Methods:

• Attackers can spoof trusted servers to intercept data or cause disruptions by manipulating the specified destination.
• Common attack patterns include using UDP packet spoofing to disguise the source of an attack, and exploiting vulnerabilities like Server-Side Request Forgery (SSRF) or XML External Entity (XXE) to redirect communications.

• Security Impact:

• Direct consequences include data interception, unauthorized data access, and denial of service.
• Potential cascading effects involve data leaks, unauthorized system access, and network disruptions.
• Business impact could include loss of customer trust, regulatory fines, and financial losses due to service downtime.

• Prevention Guidelines:

• Specific code-level fixes include validating and sanitizing destination inputs and using secure communication protocols that verify destination integrity.
• Security best practices involve regular security audits, implementing least privilege access, and ensuring proper configuration management.
• Recommended tools and frameworks include using intrusion detection systems, network firewalls, and employing libraries that reinforce secure communication standards.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Mobile

Vulnerable Code Example

const http = require('http');

function sendRequest(path, data, callback) {
    // Vulnerable: Path is directly taken from user input without validation
    const options = {
        hostname: 'example.com',
        port: 80,
        path: path,  // Path should be validated
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        }
    };

    // Sending request to a potentially incorrect path
    const req = http.request(options, (res) => {
        let responseData = '';
        res.on('data', (chunk) => {
            responseData += chunk;
        });
        res.on('end', () => {
            callback(null, responseData);
        });
    });

    req.on('error', (e) => {
        callback(e);
    });

    req.write(JSON.stringify(data));
    req.end();
}

Explanation

In this vulnerable code example, the path parameter is directly taken from user input and used in an HTTP request without any validation. This could allow an attacker to specify arbitrary paths, potentially accessing unauthorized resources or causing unintended actions on the server.

How to fix Incorrectly Specified Destination in a Communication Channel?

To mitigate this vulnerability, validate and sanitize the path parameter before using it in an HTTP request. Ensure that the path is within an expected set of paths or conforms to a specific pattern. This prevents unauthorized access and misuse of the HTTP client to access unintended resources on the server. By implementing strict validation logic, you reduce the risk of security breaches such as unauthorized data access or command injection.

Fixed Code Example

const http = require('http');

function isValidPath(path) {
    // Define valid paths or patterns
    const validPaths = ['/api/resource', '/api/another-resource'];
    return validPaths.includes(path);
}

function sendRequest(path, data, callback) {
    if (!isValidPath(path)) {
        throw new Error("Invalid path specified");
    }

    const options = {
        hostname: 'example.com',
        port: 80,
        path: path,  // Path validation ensures it's safe to use
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        }
    };

    const req = http.request(options, (res) => {
        let responseData = '';
        res.on('data', (chunk) => {
            responseData += chunk;
        });
        res.on('end', () => {
            callback(null, responseData);
        });
    });

    req.on('error', (e) => {
        callback(e);
    });

    req.write(JSON.stringify(data));
    req.end();
}

Explanation

In the fixed code example, the function isValidPath is introduced to validate the path parameter. It checks whether the path is within a predefined set of valid paths. If the path is not valid, an error is thrown, preventing the request from being sent. This ensures that only authorized paths are used in HTTP requests, mitigating the risk of incorrect or malicious paths being specified.