CWE-303: Incorrect Implementation of Authentication Algorithm

What is Incorrect Implementation of Authentication Algorithm?

• Overview: Incorrect Implementation of Authentication Algorithm (CWE-303) occurs when a product requires the use of a specific authentication algorithm, but the implementation is flawed, potentially allowing attackers to bypass authentication mechanisms.

• Exploitation Methods:

• Attackers can exploit this vulnerability by identifying discrepancies between the intended algorithm and its flawed implementation.
• Common attack patterns include reverse engineering the authentication process, exploiting logic flaws, and using brute force to bypass weak authentication checks.

• Security Impact:

• Direct consequences of successful exploitation include unauthorized access to systems and data.
• Potential cascading effects may involve further system compromises, data breaches, and privilege escalation.
• Business impact can be severe, leading to reputational damage, financial losses, and legal liabilities due to data privacy violations.

• Prevention Guidelines:

• Specific code-level fixes include thoroughly reviewing and testing authentication code to ensure it adheres to algorithm specifications.
• Security best practices involve using well-tested and peer-reviewed cryptographic libraries and avoiding homemade or unproven implementations.
• Recommended tools and frameworks include static analysis tools to detect logic errors and automated testing frameworks to validate authentication processes against expected behavior.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

const crypto = require('crypto');

function authenticateUser(username, password) {
    // Vulnerable: Incorrectly using SHA-1 for password hashing
    // SHA-1 is considered weak and susceptible to collision attacks
    const hashedPassword = crypto.createHash('sha1').update(password).digest('hex');
    // Assume usersDb is an object with username as key and hashed password as value
    if (usersDb[username] === hashedPassword) {
        return true;
    }
    return false;
}

How to fix Incorrect Implementation of Authentication Algorithm?

To address the vulnerability, replace the insecure SHA-1 hashing with a more robust solution like bcrypt. Bcrypt provides better security as it is computationally expensive and automatically incorporates a salt. Use a reputable library such as bcrypt in Node.js to handle password hashing securely.

Fixed Code Example

const bcrypt = require('bcrypt');  // Import bcrypt for secure password hashing

async function authenticateUser(username, password) {
    // Secure: Using bcrypt for password hashing
    // Ensure the usersDb contains hashed passwords generated with bcrypt
    if (usersDb[username]) {
        // Check if the provided password matches the stored hashed password
        const match = await bcrypt.compare(password, usersDb[username]);
        if (match) {
            return true;
        }
    }
    return false;
}

Explanation of the Fix:

• Use of bcrypt: The fixed code uses bcrypt, which is a widely recommended library for password hashing. It is designed to be computationally intensive, making brute-force attacks more difficult.
• Asynchronous Operations: Bcrypt operations are asynchronous, which is important for performance in a Node.js environment.
• Salting and Hashing: Bcrypt automatically handles salting and hashing, which adds an additional layer of security by ensuring that even identical passwords have different hashes.

By using bcrypt, the authentication process becomes more resistant to attacks such as brute force and rainbow table attacks, significantly improving the security posture of the application.