dex2jar - Jar反混淆 #

Introduction #

dex-tool-0.0.9.8 add support to DeObfuscate a jar

Details #

The Problem, for a Obfuscated jar like this:

package a;
public class a
{
  static String a = "Hello";
  static void a() {
    System.out.println(a);
  }
  public static void main(String[] args) {
    a();
  }
}

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all package,class,field,method names are 'a', which is difficult to read.

DeObfuscate It #

run the following command

# generate a 'suggest' config for rename
> d2j-init-deobf -f -o init.txt a.jar

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we got a init.txt

p a=pa
c a/a=C000_a
m a/a.a()=Ma
m a/a.a=Fa

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which means

#rename package a to pa
p a=pa
#rename class a to C000_a
c a/a=C000_a
#rename method a to Ma
m a/a.a()=Ma
#rename field a to Fa
m a/a.a=Fa

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modify init.txt to

#rename package a to hello
p a=hello
#rename class a to World
c a/a=World
#rename method a to say
m a/a.a()=say
#rename field a to message
m a/a.a=message

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and run

> d2j-jar-remap -f -c init.txt -o a-deobf.jar a.jar

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now we get the comfortable source

package hello;

import java.io.PrintStream;

public class World{
  static String message = "Hello";

  static void say() {
    System.out.println(message);
  }

  public static void main(String[] args) {
    say();
  }}

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or run the program with

> java -cp a-deobf.jar hello.World

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或者说Jar反混淆 #

• 1）先从工具读取jar中所有的类、字段、方法，生成一个文本的配置文件；
• 2）利用d2j-jar-remap.bat (在dex2jar工具包中)中对其进行重命名；

Reference