de4js

de4js Description

de4js is a JavaScript source code deobfuscator and unpacker.

Features:

• Works offline.
• Makes the source code readable, looks nice, syntax highlighting.
• Makes obfuscated code readable.
• Supports (de-obfuscates) the result of the following tools, services, methods:
• Eval, used for example in Packer, WiseLoop
• Array, used for example in Javascript Obfuscator, Free JS Obfuscator
• _Number
• Packer
• Javascript Obfuscator
• Free JS Obfuscator
• Obfuscator.IO (but does not always work, as this service is frequently updated, which requires updating the deobfuscator)
• My Obfuscate
• Кодирование URL, used for example in bookmarklet
• JSFuck
• JJencode
• AAencode
• WiseLoop

Homepage: https://github.com/lelinhtinh/de4js

Author: Thành Thân Thiện

License: MIT

de4js Help

de4js runs as a small server to which you can connect with a web browser. That is, the program has a web interface.

In the web interface, select one of the following methods for entering obfuscated source code:

• String – insert code into the web interface window
• Local File – select a local file on the computer
• Remote File – specify the URL address of a remote file

Below you can specify the way the JavaScript code was obfuscated:

• None
• Eval
• Array
• Obfuscator IO
• _Number
• JSFuck
• JJencode
• AAencode
• URLencode
• Packer
• JS Obfuscator
• My Obfuscate
• Wise Eval
• Wise Function
• Clean Source
• Unreadable

Alternatively, you can click the “Auto Decode” button for de4js to automatically detect the obfuscation method. The deobfuscated code will be shown in the window below.

Additional options that you can turn on or off:

• Line numbers – show line numbers
• Format Code – code formatting and syntax highlighting
• Unescape strings – convert strings from escaped sequences to normal form
• Recover object-path – restore object-path
• Execute expression – perform arithmetic and other operations on expressions
• Merge strings - concatenate strings
• Remove grouping

Deobfuscation Obfuscator.IO

The author of the Obfuscator.IO website is looking for programs that are able to deobfuscate the code created on this service and constantly changes, fixes obfuscation, as a result of which the deobfuscation tools stop working. Therefore, automatic deobfuscation tools (including de4js) usually lag behind the most recent version, that is, they can deobfuscate the code created earlier on Obfuscator.IO, but cannot deobfuscate the latest version of the code. But this does not mean that this is a reliable tool to secure your source code – projects regularly appear that bypass all deobfuscation methods. In addition, custom-made specialists can deobfuscate any code.

de4js Usage Example

Go to the folder with the program:

cd bin/de4js

Start the server:

npm start

In a web browser open the address http://127.0.0.1:4000/de4js/

How to install de4js

Installation on Kali Linux

Installing the required packages:

sudo apt install npm ruby-dev zlib1g-dev
sudo gem install bundler

Getting source code and installing dependencies:

git clone https://github.com/lelinhtinh/de4js
cd de4js
bundle install

Installing Workbox CLI:

sudo npm install workbox-cli --global

Server start:

npm start

Or with a real-time usage output:

npm run watch

De4js is now available in the web browser at: http://localhost:4000/de4js/

Build:

npm run build

Installation on BlackArch

Installing the required packages:

sudo pacman -S npm ruby zlib
sudo gem install bundler

Getting source code and installing dependencies:

git clone https://github.com/lelinhtinh/de4js
cd de4js
bundle install

Installing Workbox CLI:

sudo npm install workbox-cli --global

Server start:

npm start

Or with a real-time usage output:

npm run watch

De4js is now available in the web browser at: http://localhost:4000/de4js/

Build:

npm run build

Installation on Debian, Linux Mint, Ubuntu

Installing the required packages:

sudo apt update
sudo apt install git npm ruby-dev zlib1g-dev
sudo gem install bundler

Getting source code and installing dependencies:

git clone https://github.com/lelinhtinh/de4js
cd de4js
bundle install

Installing Workbox CLI:

sudo npm install workbox-cli --global

Server start:

npm start

Or with a real-time usage output:

npm run watch

De4js is now available in the web browser at: http://localhost:4000/de4js/

de4js Screenshots

de4js Tutorials

• How to deobfuscate JavaScript code
• How to see JavaScript code written using unprintable characters
• JavaScript Attacks