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[ShaktiCTF 2025][Forensics] Binary Reflection

Type
CTF
๋…„๋„
2025
Name
ShaktiCTF
๋ถ„์•ผ
Forensics
์„ธ๋ถ€๋ถ„์•ผ
Basic
์—ด
2025/07/28 06:28
1 more property

# Description

The truth is hidden in a mirror
Plain Text
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# ๋ถ„์„

PDF ํŒŒ์ผ ํ•˜๋‚˜๋ฅผ ์ค€๋‹ค.
ํ•ด๋‹น ํŒŒ์ผ์„ ์—ด์–ด๋ณด๋ฉด ์—ด ์ˆ˜ ์—†๋Š” ํ˜•์‹์ด๋ผ๊ณ  ๋œจ๋ฉฐ, bin ํŒŒ์ผ๋กœ ๋ณ€ํ™˜ํ•˜์—ฌ ๋ณด๋ฉด ์•„๋ž˜์™€ ๊ฐ™์ด ๋ณด์ธ๋‹ค.
ํ˜•์‹์„ ๋ณด๋ฉด %;EOF๊ฐ€ ์ฒซ ์‹œ์ž‘ ์ง€์ ์— ์žˆ๋Š” ๊ฒƒ, String ๋ฌธ์ž์—ด ๋“ค์ด ์›ํ˜•ํƒœ ๊ทธ๋Œ€๋กœ ์กด์žฌํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋ณด์•„ ํ•œ ์ค„ ์”ฉ ์—ญ์ˆœ์œผ๋กœ ๋ฐ์ดํ„ฐ๋ฅผ ์จ ๋‘” ๊ฒƒ์œผ๋กœ ์ถ”์ธกํ•  ์ˆ˜ ์žˆ๋‹ค.

# Payload

with open('corrupt copy.bin', 'rb')as f: data = f.readlines()[::-1] with open('a.pdf', 'wb')as f: for d_ in data: f.write(d_)
Python
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ํ•ด๋‹น ์ฝ”๋“œ๋กœ ํŒŒ์ผ์„ ์ฝ์–ด์„œ a.pdf๋ฅผ ๋ณด๋ฉด ๋งจ ๋ฐ‘์— flag๊ฐ€ ์จ์žˆ๋‹ค.

# Flag

shaktictf{pdf_pr3tty_d4m4g3d_f0rm4t}
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