Skip to main content

Debugging enabled in production

Need​

Disabling debugging mode in production environment

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 Servlets

Description​

Non compliant code​

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

public class DebugServlet extends HttpServlet {
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        // Debugging enabled in production
        getServletContext().setInitParameter("debug", "true");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // some code here
    }
}

The above code shows a Servlet where the debug mode is set to true in the init method. This method is called once when the servlet is first created, and it is common to perform any global setup procedures here. The getServletContext().setInitParameter("debug", "true") line is where the debug mode is turned on.

The problem with this is that if an error occurs anywhere in your application, detailed error messages (including stack traces, variable values at the time of the error, etc.) will be sent back to the client. This information can be used by an attacker to gain insights into the inner workings of your code, which could lead to further attacks.

In a production environment, you should always set the debug mode to false to prevent this kind of information leakage. Detailed error messages should be logged on the server side, not sent to the client.

Steps​

  • Disable debugging mode in production
  • Remove or comment out the line that sets the 'debug' parameter to 'true'

Compliant code​

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

public class DebugServlet extends HttpServlet {
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        // Debugging disabled in production
        // getServletContext().setInitParameter("debug", "true");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // some code here
    }
}

The above code is a fixed version of the previously vulnerable code. The vulnerability was that the debug mode was enabled in a production environment. This could lead to information leaks when an error is generated, as detailed error messages (which could potentially contain sensitive information) would be displayed.

In the fixed code, the line that enabled the debug mode (getServletContext().setInitParameter("debug", "true");) has been commented out. This effectively disables the debug mode in the production environment, mitigating the information leak vulnerability.

It's important to note that while debugging can be a useful tool during development, it should always be disabled in a production environment to prevent potential security risks.

References​

Last updated on