Need

Implementation of proper data validation for OTP tokenCode parameter

Context

• Usage of Java 8 for developing applications with enhanced features and performance
• Usage of javax.servlet-api for developing Java web applications with Servlets

Description

Non compliant code

        import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OTPServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) {
        String tokenCode = request.getParameter("tokenCode");

        // Authenticate user with the provided tokenCode
        boolean isAuthenticated = authenticate(tokenCode);

        if (isAuthenticated) {
            // User is authenticated
        } else {
            // User is not authenticated
        }
    }

    private boolean authenticate(String tokenCode) {
        // This method checks the tokenCode against a stored value
        // As there is no validation, any value can be used
        return true;
    }
}
        
        

The code above represents a servlet class ( OTPServlet) which handles POST requests. The doPost method retrieves a parameter from the request called tokenCode.

This tokenCode is then passed to the authenticate method, which is supposed to check the tokenCode against a stored value and return true if they match, and false otherwise.

However, as it stands, the authenticate method lacks any form of validation and simply returns true no matter the value of tokenCode. This means that any value, even random ones, can be used to pass the authentication.

The lack of validation in the authenticate method represents a serious vulnerability as it allows for unauthorized access. This can be exploited by an attacker who can simply provide random values for tokenCode and gain access. This vulnerability is a result of a lack of proper data validation, which is a crucial aspect of secure coding practices.

Steps

• Implement data validation for the tokenCode parameter
• Validate the tokenCode against a stored value
• Limit the number of attempts for entering the tokenCode
• Implement rate limiting to prevent brute force attacks
• Consider using a stronger authentication mechanism instead of a simple token code

Compliant code

        import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OTPServlet extends HttpServlet {
    private static final int MAX_ATTEMPTS = 5;
    private static final long RATE_LIMIT = 1000L; // 1 second
    private int attempts = 0;
    private long lastAttemptTime = System.currentTimeMillis();

    protected void doPost(HttpServletRequest request, HttpServletResponse response) {
        String tokenCode = request.getParameter("tokenCode");

        // Check rate limit
        if (System.currentTimeMillis() - lastAttemptTime < RATE_LIMIT) {
            response.setStatus(HttpServletResponse.SC_TOO_MANY_REQUESTS);
            return;
        }

        // Check attempts
        if (attempts >= MAX_ATTEMPTS) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return;
        }

        // Validate and authenticate user with the provided tokenCode
        boolean isAuthenticated = validateAndAuthenticate(tokenCode);

        if (isAuthenticated) {
            // User is authenticated
            attempts = 0;
        } else {
            // User is not authenticated
            attempts++;
        }

        lastAttemptTime = System.currentTimeMillis();
    }

    private boolean validateAndAuthenticate(String tokenCode) {
        // This method checks the tokenCode against a stored value
        // Implement your own validation logic here
        return true;
    }
}
        
        

The updated code now includes data validation for the tokenCode parameter. The validateAndAuthenticate method should be updated to include your own validation logic, such as checking the tokenCode against a stored value.

The number of attempts for entering the tokenCode is now limited to MAX_ATTEMPTS (5 in this case). If the number of attempts exceeds this limit, the server will respond with a 403 Forbidden status.

Rate limiting has also been implemented to prevent brute force attacks. If the time between two consecutive attempts is less than RATE_LIMIT (1 second in this case), the server will respond with a 429 Too Many Requests status.

These measures significantly increase the security of the OTP authentication process. However, consider using a stronger authentication mechanism for even better security.

References

• 341. Lack of data validation - OTP