JavaScript Deobfuscation

Javascript Deobfuscation

Introduction:

Code deobfuscation is an important skill to learn if we want to be skilled in code analysis and reverse engineering. Obfuscation is a technique used to make a script more difficult to read by humans but allows it to function the same from a technical point of view, though performance may be slower.This article will explain what is code deobfuscation, the reasons for using it, and its potential advantages and disadvantages.

Deobfuscated code:

This is usually achieved automatically by using an obfuscation tool, which takes code as input, and attempts to re-write the code in a way that is much more difficult to read, depending on its design

For example consider the following two snippets of code and their output

Snippet 1:

console.log("Hello by Dhanush")

Output of Snippet 1:

Hello by Dhanush

Snippet 2:

eval(
  (function (p, a, c, k, e, d) {
    e = function (c) {
      return c;
    };
    if (!"".replace(/^/, String)) {
      while (c--) {
        d[c] = k[c] || c;
      }
      k = [
        function (e) {
          return d[e];
        },
      ];
      e = function () {
        return "\\w+";
      };
      c = 1;
    }
    while (c--) {…