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Security controls bypass or absence - Fingerprint

Need​

Enhancement of security controls for fingerprint identification

Context​

  • Usage of C# for building robust and scalable applications
  • No usage of any specific library or dependency

Description​

Non compliant code​

public class FingerprintAuthentication
{
    public bool AuthenticateUser(string username, string password)
    {
        // Check if user exists
        var user = GetUser(username, password);
        if (user != null)
        {
            // User exists, bypass fingerprint authentication
            return true;
        }
        return false;
    }

    private User GetUser(string username, string password)
    {
        // This is a placeholder for actual implementation. 
        // In real-world application, this should query the database to retrieve the user.
        return null;
    }
}

public class User
{
    public string Username { get; set; }
    public string Password { get; set; }
}

The above code represents a class FingerprintAuthentication which is responsible for authenticating users. The AuthenticateUser method takes a username and password as parameters and checks if the user exists by calling the GetUser method. If the user exists, the method returns true, indicating that the user is authenticated.

However, this code is vulnerable due to the absence of fingerprint authentication. Even though the class is named FingerprintAuthentication, there's no actual implementation of fingerprint authentication. It simply checks if the user exists and if so, the user is considered authenticated. This allows an attacker to bypass the fingerprint authentication by simply knowing the username and password of a user.

In a real-world application, this could lead to unauthorized access to the system, as the attacker would not need to provide the user's fingerprint, which is a critical security control. This absence of security control is a serious vulnerability and should be addressed immediately.

Steps​

  • Implement a proper fingerprint authentication mechanism.
  • Do not bypass fingerprint authentication based on the existence of a user.
  • Ensure that the fingerprint authentication is performed before any other authentication checks.
  • Store and compare the fingerprint data securely.
  • Regularly update and patch the fingerprint authentication system to address any vulnerabilities.

Compliant code​

public class FingerprintAuthentication
{
    public bool AuthenticateUser(string username, string password, string fingerprintData)
    {
        // Check if user exists
        var user = GetUser(username, password);
        if (user != null)
        {
            // User exists, now authenticate with fingerprint
            return AuthenticateFingerprint(fingerprintData);
        }
        return false;
    }

    private User GetUser(string username, string password)
    {
        // This is a placeholder for actual implementation. 
        // In real-world application, this should query the database to retrieve the user.
        return null;
    }

    private bool AuthenticateFingerprint(string fingerprintData)
    {
        // This is a placeholder for actual implementation.
        // In real-world application, this should compare the provided fingerprint data with the stored one.
        return false;
    }
}

public class User
{
    public string Username { get; set; }
    public string Password { get; set; }
    public string FingerprintData { get; set; }
}

The updated code now includes a proper fingerprint authentication mechanism. The AuthenticateUser method now requires an additional parameter fingerprintData. This data should be the fingerprint information captured from the user trying to authenticate.

The existence of a user is still checked first, but now, instead of bypassing the fingerprint authentication, it is a necessary step. If the user exists, the AuthenticateFingerprint method is called, which should contain the logic to authenticate the user based on the provided fingerprint data.

The User class now also includes a FingerprintData property. This should store the fingerprint data of the user. In a real-world application, this data should be stored securely and compared with the provided fingerprint data during authentication.

Remember to regularly update and patch the fingerprint authentication system to address any vulnerabilities. This includes keeping up-to-date with the latest fingerprint recognition technologies and security practices.

References​

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