General purpose JavaScript deobfuscator

A simple but powerful deobfuscator to remove common JavaScript obfuscation techniques.
Open an issue if there is a feature you think should be implemented.

Online version at deobfuscate.io

Install via npm install js-deobfuscator

Looking for a deobfuscator specific to Obfuscator.io/javascript-obfuscator? Try this repo

If you would like to discuss/learn about JavaScript obfuscation and deobfuscation you can join the Discord server

Features

- Unpacks arrays containing literals (strings, numbers etc) and replaces all references to them
- Removes simple proxy functions (calls to another function), array proxy functions and arithmetic proxy functions (binary expressions)
- Simplifies arithmetic expressions
- Simplifies string concatenation
- Renames unreadable hexadecimal identifiers (e.g. \_0xca830a)
- Converts computed to static member expressions and beautifies the code

Examples

See bottom for more complicated example with features chained together.

$3

Before

``javascript
const a = ['\x20', '\x57\x6f\x72\x6c\x64', '\x48\x65\x6c\x6c\x6f'];

console.log(a[2] + a[0] + a[1]);
`

After

`javascript
console.log('Hello' + ' ' + 'World');
`

$3

#### An example with simple proxy functions for other functions

Before

`javascript
function a(b, c) {
return someFunction(b, c);
}

const result = a(5, 6);
`

After

`javascript
const result = someFunction(5, 6);
`

#### An example with proxy functions for arithmetic

Before

`javascript
function a(b, c) {
return c + 2 * b;
}

const result = a(5, 6);
`

After

`javascript
const result = 6 + 2 * 5;
`

#### An example with chained proxy functions

Before

`javascript
function a(b, c) {
return c + 2 * b;
}
function b(c, d) {
return a(c, d);
}
function c(d, e) {
return b(d, e);
}

const result = c(5, 6);
`

After

`javascript
const result = 6 + 2 * 5;
`

$3

#### An example with numbers

Before

`javascript
let total = 0x2 0x109e + -0xc -0x16a + -0x3234;
for (let i = 0x1196 + 0x97b 0x3 + -0x2e07; i < -0x95 -0x38 + -0x1a75 + -0x619; i++) {
total += i;
}
`

After

`javascript
let total = 0;
for (let i = 0; i < 10; i++) {
total += i;
}
`

#### An example with strings.

Before

`javascript
console.log('He' + 'll' + 'o' + ' Wo' + 'r' + 'ld');
`

After

`javascript
console.log('Hello World');
`

$3

All these features can be chained together to simplify code.

Before

`javascript
const ar = [
'\x48\x65\x6c\x6c\x6f',
0x95,
'\x20',
0x1a75,
'\x57\x6f\x72\x6c\x64',
-0x53,
'\x6c\x6f\x67'
];
const a = function (b, c) {
return c + 2 * b;
},
b = function (c, d) {
return a(c, d);
},
c = function (d, e) {
return b(d, e);
};
const message = ar[0] + ar[2] + ar[4];
const result = c(ar[1] 0x38 + ar[3] + 0x619, 0x12 ar[5] + 0x1a13 + 0x621);
console[ar[6]](message + ' ' + result);
`

After

`javascript
const message = 'Hello World';
const result = 40106;
console.log(message + ' ' + result);
`

Config

`typescript
interface Config {
verbose: boolean;
isModule: boolean;
arrays: {
unpackArrays: boolean;
removeArrays: boolean;
};
proxyFunctions: {
replaceProxyFunctions: boolean;
removeProxyFunctions: boolean;
};
expressions: {
simplifyExpressions: boolean;
removeDeadBranches: boolean;
};
miscellaneous: {
beautify: boolean;
simplifyProperties: boolean;
renameHexIdentifiers: boolean;
};
}
`

To Run

Either install the module locally via npm install js-deobfuscator and import as usual or install globally npm install -g js-deobfuscator and use the js-deobfuscator CLI:

`shell
> js-deobfuscator -h
Usage: js-deobfuscator [options]

Deobfuscate a javascript file

Options:
-i, --input [input_file] The input file to deobfuscate (default: "input/source.js")
-o, --output [output_file] The deobfuscated output file (default: "output/output.js")
-m, --module Parse an ESModule
-h, --help display help for command
``

Alternatively use the online version at deobfuscate.io