> For the complete documentation index, see [llms.txt](https://docs.cooku222.kr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cooku222.kr/security/mobile/frida-lab/frida-labs-0x7.md).

# Frida-Labs 0x7

출처: <https://github.com/DERE-ad2001/Frida-Labs/tree/main/Frida%200x7>

***

```
C:\Users\after\Downloads>adb install Challenge_0x7.apk
Performing Streamed Install
Success
```

마찬가지로 설치로 시작

<figure><img src="https://blog.kakaocdn.net/dna/BB6XQ/dJMcacPCzg4/AAAAAAAAAAAAAAAAAAAAAMTA_rtgopcFZB1-MeFaKO_gp5vy0R0Xon5pknnOx4lE/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=Nqe%2FtbGRsr7EgmyORYuxzrPGDyg%3D" alt="" height="223" width="1363"><figcaption></figcaption></figure>

Checker에서 받는 인자 A의 num1, num2이 512보다 커야한다.&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/cHgJDH/dJMcadnpCaz/AAAAAAAAAAAAAAAAAAAAAO8Bx2MJKtSqqX5FIKAj5WrSai6XM9rMOsip_CgAa0ca/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=aySMz0opawJXvWKUGN4f87iZ2%2BM%3D" alt="" height="387" width="490"><figcaption></figcaption></figure>

Checker의 형태는 이렇게 생겼다.&#x20;

```
Java.performNow(function() {
  Java.choose('com.ad2001.frida0x7.MainActivity', {
    onMatch: function(instance) {
    console.log("Instance found");

    var checker = Java.use("com.ad2001.frida0x7.Checker");
    var checker_obj  = checker.$new(600, 600); // Class Object
    instance.flag(checker_obj); // invoking the get_flag method
  },
    onComplete: function() {}
  });
});
```

Frida 자바스크립트 코드만 보면 이런데, 인스턴스에 넣어주는 값에 어차피 512만 크면 되니 깔끔하게 600으로 넣어준다. 그리고 flag()를 후킹하는 함수를 만들어준다.

```
C:\Users\after\Downloads>frida -U -f com.ad2001.frida0x7
     ____
    / _  |   Frida 17.5.1 - A world-class dynamic instrumentation toolkit
   | (_| |
    > _  |   Commands:
   /_/ |_|       help      -> Displays the help system
   . . . .       object?   -> Display information about 'object'
   . . . .       exit/quit -> Exit
   . . . .
   . . . .   More info at https://frida.re/docs/home/
   . . . .
   . . . .   Connected to Android Emulator 5554 (id=emulator-5554)
Spawned `com.ad2001.frida0x7`. Resuming main thread!
[Android Emulator 5554::com.ad2001.frida0x7 ]-> Java.performNow(function() {
  Java.choose('com.ad2001.frida0x7.MainActivity', {
    onMatch: function(instance) {
    console.log("Instance found");

    var checker = Java.use("com.ad2001.frida0x7.Checker");
    var checker_obj  = checker.$new(600, 600); // Class Object
    instance.flag(checker_obj); // invoking the get_flag method
  },
    onComplete: function() {}
  });
});
Instance found
```

&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/bovxg5/dJMcadHHXVq/AAAAAAAAAAAAAAAAAAAAABZxPac-zhc6TTw2FcWIri-nJxXwrODteV6wl85oX4Gm/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=uQwRBMNx5J%2FKVwErh9o1jUKdmXQ%3D" alt="" height="555" width="283"><figcaption></figcaption></figure>

&#x20;


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