CWE-654: Reliance on a Single Factor in a Security Decision

What is Reliance on a Single Factor in a Security Decision?

• Overview: Reliance on a Single Factor in a Security Decision occurs when a security mechanism depends solely on one condition or element to authorize access or perform sensitive operations, making it vulnerable if that single factor is compromised.

• Exploitation Methods:

• Attackers can exploit this vulnerability by bypassing the single control measure, such as manipulating a single authentication token or certificate.
• Common attack patterns include spoofing the single factor (e.g., forging credentials) or exploiting weaknesses in the verification process of that factor.

• Security Impact:

• Direct consequences of successful exploitation include unauthorized access to protected resources or functionalities.
• Potential cascading effects involve further compromise of systems, leading to data breaches or system control.
• Business impact can be significant, including loss of sensitive data, financial loss, and damage to reputation.

• Prevention Guidelines:

• Specific code-level fixes include implementing multi-factor authentication (MFA) to require multiple proofs of identity.
• Security best practices involve layering security measures and ensuring no single point of failure in access controls.
• Recommended tools and frameworks include using libraries and services that support MFA and regularly auditing security controls for effectiveness.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

function authenticateUser(username, token) {
    // Vulnerable: Authentication relies solely on a single token
    // An attacker with access to the token can impersonate the user
    return token === "hardcoded_token";
}

How to fix Reliance on a Single Factor in a Security Decision?

To mitigate this vulnerability, implement multi-factor authentication. This provides an additional layer of security by requiring more than one form of verification. In the JavaScript context, you can use a combination of:

1. A secure password or PIN.
2. A time-based one-time password (TOTP) from an authenticator app.
3. Biometrics or a physical security key.

Using these methods ensures that even if one authentication factor is compromised, unauthorized access is prevented by the additional required factors.

Fixed Code Example

function authenticateUser(username, password, token) {
    // Fixed: Implementing multi-factor authentication
    // Verify both password and token to strengthen authentication
    if (!verifyPassword(username, password)) {
        return false;
    }
    return verifyToken(username, token);
}

function verifyPassword(username, password) {
    // Securely check the password using a hash comparison
    // This is a placeholder for actual password verification logic
    const storedPasswordHash = getPasswordHashForUser(username);
    return hash(password) === storedPasswordHash;
}

function verifyToken(username, token) {
    // Securely verify the token using TOTP or another method
    // This is a placeholder for actual token verification logic
    return validateTOTP(username, token);
}

function getPasswordHashForUser(username) {
    // Placeholder function to retrieve stored password hash for a user
    return "hashed_password_from_db";
}

function hash(input) {
    // Placeholder hash function
    return "hashed_" + input;
}

function validateTOTP(username, token) {
    // Placeholder function for TOTP validation
    return token === "expected_totp_token";
}

Key Improvements:

• Separation of Concerns: Functions are split to handle password and token verification separately, enhancing clarity and maintainability.
• Security Best Practices: Illustrates the use of hashed passwords and TOTP for token verification, which is a more secure approach than hardcoded values.
• Comments: Added detailed comments to explain the security improvements and placeholders for actual implementation logic.
• Realism: The fixed example provides a more realistic scenario by simulating password hashing and token validation, which are common practices in secure authentication systems.