Node inspector/CEF debug abuse

👉 Overview

👀 What ?

Linux Node inspector and CEF debug are tools and techniques used for debugging applications in a Linux environment. Node inspector is a debugging interface for Node.js applications and CEF debug is a debugging mode for applications that use the Chromium Embedded Framework.

🧐 Why ?

Debugging is a critical process in software development and maintenance. It helps developers identify and fix errors in their code, leading to more reliable and efficient applications. Debugging is also crucial in cybersecurity as it allows security researchers to understand how malicious software operates and how to counter it.

⛏️ How ?

To use Node inspector, start your Node.js application with the --inspect flag. This will start the inspector and give you a URL that you can open in your browser to start debugging. For CEF debug, you can start your application with the --remote-debugging-port flag followed by a port number. You can then connect to this port with a browser to start debugging. Both these tools allow you to step through your code, set breakpoints, and inspect variables.

⏳ When ?

You should use Node inspector and CEF debug whenever you need to debug a Node.js or CEF application. This could be during development, when you are trying to understand how your code is behaving, or it could be during a security investigation, when you are trying to understand how a piece of malicious software is behaving.

⚙️ Technical Explanations

Node Inspector and Chromium Embedded Framework (CEF) Debug are powerful tools for debugging applications, particularly in a Linux environment.

Node Inspector is a debugging interface specifically designed for Node.js applications. It operates by initiating a WebSocket server within your Node.js application. This server interfaces with your web browser, allowing you to debug your application interactively. When you start your Node.js application with the '--inspect' flag, the Node Inspector initiates and provides you with a URL. You can then open this URL in your web browser to commence the debugging process. This tool enables you to step through your code, set breakpoints, and inspect variables.

On the other hand, CEF Debug is a debugging mode designed for applications that utilize the Chromium Embedded Framework. Like Node Inspector, CEF Debug also allows interactive debugging. Instead of running a WebSocket server, CEF Debug operates by initiating an HTTP server that your web browser can connect to. This server offers a JSON-based API which allows you to manipulate and inspect your application. To use CEF Debug, you should start your application with the '--remote-debugging-port' flag followed by a port number. Then, by connecting to this port with a browser, you can start the debugging process.

Both Node Inspector and CEF Debug are essential tools when debugging during development or conducting a security investigation. They offer insight into your application's behavior and help identify and rectify coding errors, resulting in more reliable and efficient applications. Moreover, these tools are pivotal in cybersecurity, allowing researchers to understand the operations of malicious software and devise appropriate countermeasures.

Let's look at a detailed example of how to use Node Inspector and CEF Debug for debugging.

Node Inspector:

Imagine we have a simple Node.js application that increments a counter. Our code might look something like this:

let counter = 0;

setInterval(() => {
    counter++;
    console.log(`Counter: ${counter}`);
}, 1000);

To debug this application with Node Inspector, we would start the application with the --inspect flag:

node --inspect counter.js

This will provide a URL that we can open in a web browser, such as Chrome. The URL will look something like this: chrome-devtools://devtools/bundled/js_app.html?experiments=true&v8only=true&ws=127.0.0.1:9229/0f2c936f-b1cd-4ac9-aab3-f63b0f33d55e.

When we open this URL, we can set breakpoints in our code, step through the code, and inspect variables.

CEF Debug:

Now suppose we have an application that uses the Chromium Embedded Framework. To debug this application, we would start it with the --remote-debugging-port flag followed by a port number:

./my_cef_application --remote-debugging-port=9222

We can then connect to this port with a web browser by navigating to: http://localhost:9222. This will present us with a list of active pages in our application. Clicking on one of these will open a new debugging session, where we can inspect elements, view console output, and debug JavaScript.

Remember, Node Inspector and CEF Debug are essential tools for debugging Node.js and CEF applications. They can provide valuable insight into your application's behavior and help you identify and rectify coding errors.