Need

Implementation of a robust and secure authentication mechanism

Context

• Usage of Java for building cross-platform applications
• Usage of javax.servlet for Java web application development
• Usage of javax.servlet.http for handling HTTP requests and responses in Java web applications

Description

Non compliant code

        import javax.servlet.*;
import javax.servlet.http.*;

public class UnprotectedServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String secretData = getSecretData();
        response.getWriter().write(secretData);
    }

    private String getSecretData() {
        // Fetch secret data from database
        return "Secret Data";
    }
}
        
        

The above code represents a Servlet that handles HTTP GET requests. It fetches some secret data from a database and writes it directly to the HTTP response.

The vulnerability lies in the fact that there is no authentication mechanism present in the doGet method. Any HTTP GET request to this Servlet, regardless of the requester, will be able to receive the secret data. This is a serious security flaw as it allows anyone to access sensitive information that should be protected.

The absence of an authentication mechanism means that there's no way to verify the identity of the requester. As a result, an attacker can easily bypass the non-existent security measures and access the resources without having an active session.

To fix this, an authentication mechanism should be implemented to ensure that only authenticated and authorized users can access the secret data. This can be done using various methods such as session management, token-based authentication, or HTTP basic authentication.

Steps

• Implement an authentication mechanism to verify the identity of the user before granting access to protected resources.
• Use a secure and robust authentication method such as username/password authentication, token-based authentication, or multi-factor authentication.
• Ensure that the authentication mechanism cannot be easily bypassed or evaded by attackers.
• Enforce access control to restrict unauthorized access to sensitive resources.
• Implement session management to track and manage user sessions.
• Store sensitive data securely, such as using encryption or hashing techniques.
• Regularly update and patch the authentication mechanism to address any security vulnerabilities.
• Conduct regular security assessments and penetration testing to identify and fix any potential vulnerabilities in the authentication mechanism.

Compliant code

        import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

public class ProtectedServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession(false);
        if (session != null && session.getAttribute("username") != null) {
            String secretData = getSecretData();
            response.getWriter().write(secretData);
        } else {
            response.getWriter().write("Unauthorized access");
            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        }
    }

    private String getSecretData() {
        // Fetch secret data from database
        return "Secret Data";
    }
}
        
        

The updated code now includes an authentication mechanism to verify the identity of the user before granting access to protected resources. This is done by checking if the user has an active session and if the session contains a "username" attribute.

In the doGet method, we first retrieve the current session by calling request.getSession(false). The false parameter means that it will not create a new session if one does not already exist.

Next, we check if the session is not null and if it contains a "username" attribute. If these conditions are met, it means that the user is authenticated and we proceed to fetch and return the secret data.

If the session is null or does not contain a "username" attribute, it means that the user is not authenticated. In this case, we return an "Unauthorized access" message and set the HTTP response status to 401 (Unauthorized).

This way, we ensure that only authenticated users can access the secret data, thereby fixing the vulnerability.

Please note that this is a basic example of session-based authentication. In a real-world application, you would typically use a more secure and robust authentication method, such as username/password authentication, token-based authentication, or multi-factor authentication. You would also need to implement additional security measures, such as access control, session management, secure storage of sensitive data, regular updates and patches, and regular security assessments and penetration testing.

References

• 006. Authentication mechanism absence or evasion