> 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/owasp-mas-crackme/android-uncrackable-level2.md).

# Android UnCrackable Level2

문제 파일 : <https://mas.owasp.org/crackmes/Android/#mastg-hacking-playground>

***

<figure><img src="https://blog.kakaocdn.net/dna/CjCjY/dJMcagDS9Lr/AAAAAAAAAAAAAAAAAAAAAICK_fT5_R3XXXqukBagoEkeAfyX_6Wo7_SBDEloWcsA/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=yedXFVtwy1LpGIONhSwnbyv9BXQ%3D" alt="" height="937" width="1642"><figcaption></figcaption></figure>

주류는 녹스지만 난 블루스택으로 풀어주려 한다.

블루스택으로 L2 apk를 실행하면 위와 같이 Secret String을 입력해야만 성공이 뜨는 어플리케이션이 등장한다.&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/cyAbNT/dJMcafrroGZ/AAAAAAAAAAAAAAAAAAAAADKJ7bqT9_uFETc1DYEtgQWgqmaore13XXymKeW2yI8t/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=vx0tT1ofZ7LoB2gBTz%2Bq6hwBAPc%3D" alt="" height="692" width="1092"><figcaption></figcaption></figure>

MainActivity부터 분석하면 위와 같이 루팅이 탐지된다고 뜸.&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/dMaSxT/dJMcaaRcSgO/AAAAAAAAAAAAAAAAAAAAAOlk16QY-hRmPK4M27lWKkLOSUaR3saXjJHW6w4FO5tl/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=Oil45qrnXZ4D2fo%2B88E0QjQVAQI%3D" alt="" height="132" width="477"><figcaption></figcaption></figure>

같은 사진 하단에 CodeCheck() 부분에서 문자열을 확인하는 부분이 있음. 여기로 진입하기.&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/CwXeq/dJMcaaXYoDg/AAAAAAAAAAAAAAAAAAAAABXQyt8Vxlq8LYtVHHFEHFvp0Ruc6c26tUEonlEDAfE3/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=Vb%2FhibqSeyF%2BJV6Uw1urzBMhEiM%3D" alt="" height="260" width="550"><figcaption></figcaption></figure>

bar() 함수에서 참인지 거짓인지 판별하는게 보임. 이 bar() 함수를 뜯어봐야함.&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/oh4Ft/dJMcacIfYSe/AAAAAAAAAAAAAAAAAAAAAISNvoYcErMTgtc8tfKIX7Kn2TKlMkQHm6N4V0tFirKa/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=5y64wQQmk4QHlsA8bTU13P8oE44%3D" alt="" height="172" width="278"><figcaption></figcaption></figure>

bar() 함수는 바이너리로 되어있어서 IDA로 까준다. libfoo.so로 진입해 오른쪽 마우스 - \[export]를 하면 파일 추출이 된다.&#x20;

기드라로 bar() 함수를 까준 후 uStack\_38에 있는 문자열을 입력해주면 풀린다.

<figure><img src="https://blog.kakaocdn.net/dna/b9YxRS/dJMcaa4JZi6/AAAAAAAAAAAAAAAAAAAAADUhpY8F3_jp40aefO3_jOBiflkj_DdoJhuUbANb7MTP/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=NcObUHW0QmIloXNj4sDpw2P6PFo%3D" alt="" height="937" width="1602"><figcaption></figcaption></figure>

<figure><img src="https://blog.kakaocdn.net/dna/Xqay3/dJMcaap8ret/AAAAAAAAAAAAAAAAAAAAAJt-8rRqXn27h-eEs5zX1r2_PmI7udfjhpFHsvGNzctY/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=atnwe49oT435YvUKAnFr%2FygowKA%3D" alt="" height="287" width="877"><figcaption></figcaption></figure>

&#x20;

<br>


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