> 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/digital-forensics/dreamhack/dreamhack-vbr.md).

# \[DreamHack] VBR

<figure><img src="https://blog.kakaocdn.net/dna/6MJ6T/btsM4J3Os8X/AAAAAAAAAAAAAAAAAAAAAMVRgkH3042wtdhLiRC1shSpQFB1gc4SoR2ziejK9VoJ/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=SoB4X5qqzbVZEkowXbOccuAx2g4%3D" alt="" height="1015" width="1911"><figcaption></figcaption></figure>

&#x20;

#### 문제 링크

<https://dreamhack.io/wargame/challenges/1188>

[VBRDescription \[\\\[함께실습\\\] VBR\](https://learn.dreamhack.io/633)에서 실습하는 문제입니다. 주어진 VBR을 분석하고, 플래그를 계산하시오. Info FLAG = DH{(A + B + C)} (단, 더한 값을 십진수로 변환할 것) A: 파일시스dreamhack.io](https://dreamhack.io/wargame/challenges/1188)

***

<figure><img src="https://blog.kakaocdn.net/dna/bsVt8d/btsM22wJeQE/AAAAAAAAAAAAAAAAAAAAAMpXmzq5cG0gHA9GHzBTiLFAGDRPyHML1HgTfkOw9CKh/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=pBmfUzbeI7M7JwqiEykO2673%2Bl0%3D" alt="" height="783" width="939"><figcaption></figcaption></figure>

주의해야할 건.. zip 파일 자체가 아니라 zip 파일 압축 해제한 bin 파일 자체를 HxD로 열어준다. \
VBR과 같은 bin 파일은 보통 로우 데이터고 이런 로우 데이터는 해석이 불가능한 바이너리 파일로 이루어져 있기 때문에 바이너리 파일을 가독성 좋게 구성해주는 HxD 를 사용한다(참고로 HxD는 리버싱에서도 자주 쓰이는 툴이니 숙지하도록 하자)

<figure><img src="https://blog.kakaocdn.net/dna/kDhGb/btsM2x4F1X7/AAAAAAAAAAAAAAAAAAAAAFbgJ6e4j_GLpPf02_eBKJOxsmfv_CwX3Pr8_r2J7wD-/img.jpg?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=GTsTejwv%2FxrfpukdUBJ%2FtbPah%2B8%3D" alt="" height="333" width="759"><figcaption><p>출처 : https://c0msherl0ck.github.io/file%20system/post-VBR/</p></figcaption></figure>

해당 출처의 사진에 맞게 각각 16진수 값을 리틀 엔디언(낮은 주소에 데이터의 낮은 바이트부터 저장하는 방식으로 우리가 일반적으로 아는 선형 방식과는 거꾸로 씀) 으로 변환 후 10진수로 변환해서 계산하면 된다.\
오늘 포렌식 트랙 본격적으로 처음 들어갔는데 외워야할게 참 많다..&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/btY6vW/btsM31w7U1j/AAAAAAAAAAAAAAAAAAAAAGYLcB-cXHSi1DgcdESCS-t1Gxs_UA-i-Q7mJ-fYIT01/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=quenLwEckQeksGZ6i%2Fp9grHzJNI%3D" alt="" height="445" width="748"><figcaption></figcaption></figure>

이 부분 자세히 확인해보면 FAT 32라고 주어졌으므로 A=1

<figure><img src="https://blog.kakaocdn.net/dna/3cMsI/btsM4lvlzlk/AAAAAAAAAAAAAAAAAAAAADh3MICMTavwiEPGiSsLP4L6NCXcliT94EX147MQSAap/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=BjeTs3y58PZZS1laMnAaqubrJ8s%3D" alt="" height="567" width="756"><figcaption></figcaption></figure>

B = 0x3E8000 => 4096000

<figure><img src="https://blog.kakaocdn.net/dna/bRbG1R/btsM4mHOT2P/AAAAAAAAAAAAAAAAAAAAAIcnNXv6krVBYHtQ5_8Sd0Ur3LQKyOs86bc0sEl8_g5J/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=rVSd1DO4iYPuInvysUILRvp8CzI%3D" alt="" height="533" width="843"><figcaption></figcaption></figure>

Bytes per Sector 값은 0x00 02\
-> 변환하면 512\
-> 4096000\*512 = 2097152000\
&#x20;

<figure><img src="https://blog.kakaocdn.net/dna/PwTEj/btsM3W3ICwo/AAAAAAAAAAAAAAAAAAAAAMCtESvqcSSd1IJ7M5Y7xwjoCOlxQ-tcG8RC4nbI-6Jz/img.png?credential=yqXZFxpELC7KVnFOS48ylbz2pIh7yKj8&#x26;expires=1782831599&#x26;allow_ip=&#x26;allow_referer=&#x26;signature=z3EZweqEoshzSGAiVD312wjAQGc%3D" alt="" height="373" width="807"><figcaption></figcaption></figure>

c = 0x8A EE A8 0E -> 245952138\
A + B + C = 2343104139\
플래그는&#x20;

```
DH{2343104139}
```


---

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