๋ณธ๋ฌธ ๋ฐ”๋กœ๊ฐ€๊ธฐ

Misc3

[Dreamhack] littlevsbig Write Up โš ๏ธ littlevsbig Write Up 1. ๋ฌธ์ œ ํ™•์ธ ํ›„ ํŒŒ์ผ ๋‹ค์šด๋กœ๋“œ 2. ๋ฌธ์ œ ํŒŒ์ผ ์† chall.c ์˜คํ”ˆ ํ›„ ์ฝ”๋“œ ๋ถ„์„ --> FLAG ์ถœ๋ ฅ ์กฐ๊ฑด ๋ฐœ๊ฒฌ // Name: chall.c // Compile Option: gcc chall.c -o chall -fno-stack-protector #include #include #include #include #include #include #define FLAG_SIZE 0x45 void alarm_handler() { ใ…คใ…คputs("TIME OUT"); ใ…คใ…คexit(-1); } void initialize() { ใ…คใ…คsetvbuf(stdin, NULL, _IONBF, 0); ใ…คใ…คsetvbuf(stdout, NULL, _IONBF, 0); ใ…คใ…คsi.. 2023. 11. 28.
[Dreamhack] dreamhack-tools-cyberchef Write Up ๐ŸŒš dreamhack-tools-cyberchef Write Up 1. ๋ฌธ์ œ ์„ค๋ช… ํ™•์ธ ํ›„ ํŒŒ์ผ ๋‹ค์šด๋กœ๋“œ 2. ๋‹ค์šด๋ฐ›์€ ํŒŒ์ผ ์† index.html ์œผ๋กœ ์ ‘์† --> ์•”ํ˜ธ๋ฌธ๊ณผ ์•”ํ˜ธํ™” ์ˆœ์„œ ๋ฐœ๊ฒฌ # ์•”ํ˜ธํ™” ์ˆœ์„œ : Rail Fence → Base64 → ROT13 # ๋ณตํ˜ธํ™” ์ˆœ์„œ : ROT13 → Base64 → Rail Fence 3. ๋ฌธ์ œ์— ๋ช…์‹œ๋œ Cyberchef ์œผ๋กœ ์ ‘์† ++ Dreamhack Cyberchef --> https://tools.dreamhack.games/cyberchef dreamhack-tools tools.dreamhack.games 4. ๋ณตํ˜ธํ™” ์ˆœ์„œ์— ๋”ฐ๋ผ ์•”ํ˜ธ๋ฌธ ์ฐจ๋ก€๋กœ ๋ณตํ˜ธํ™” --> FLAG ๋ฐœ๊ฒฌ # Input : EUg5MJAyYJ9fYJ5iMKqio29iVK1VL2Wl.. 2023. 11. 27.
[Dreamhack] broken-png ๋“œ๋ฆผํ•ต ์›Œ๊ฒŒ์ž„ ๋ฌธ์ œ ํ’€์ด ๐Ÿคณ broken-png ๋“œ๋ฆผํ•ต ์›Œ๊ฒŒ์ž„ ๋ฌธ์ œ ํ’€์ด 1. ๋ฌธ์ œ์— ๋Œ€ํ•œ ์„ค๋ช…์„ ์ฝ์€ ํ›„ ๋ฌธ์ œ ํŒŒ์ผ ๋‹ค์šด๋กœ๋“œ 2. ๋‹ค์šด๋ฐ›์€ ์ด๋ฏธ์ง€ ํŒŒ์ผ ์—ด๊ธฐ --> FLAG ์ผ๋ถ€๊ฐ€ ์ž˜๋ ค์žˆ์Œ์„ ํ™•์ธ 3. HxD ์–ดํ”Œ์„ ํ†ตํ•ด ๋‹ค์šด๋ฐ›์€ ์ด๋ฏธ์ง€ ํŒŒ์ผ ์—ด๊ธฐ ++ HxD ํ”„๋กœ๊ทธ๋žจ์ด๋ž€? HxD๋Š” ์œˆ๋„์šฐ ์šด์˜ ์ฒด์ œ์—์„œ ๋™์ž‘ํ•˜๋Š” ํ”„๋ฆฌ์›จ์–ด ํ—ฅ์Šค ์—๋””ํ„ฐ๋กœ, ์ฃผ๋กœ ์ปดํ“จํ„ฐ ํŒŒ์ผ์˜ ์ด์ง„ ๋ฐ์ดํ„ฐ๋ฅผ ํŽธ์ง‘ ๋ฐ ๋ถ„์„ํ•˜๋Š” ๋„๊ตฌ๋กœ ์‚ฌ์šฉ๋œ๋‹ค. ์ด ์™ธ์—๋„ HxD๋Š” CRC(์ˆœํ™˜ ์ค‘๋ณต ๊ฒ€์‚ฌ) ์ง„ํ–‰ ๋ฐ ๋ฉ”๋ชจ๋ฆฌ ๊ฒ€์‚ฌ ๊ธฐ๋Šฅ๋„ ์ง€์›ํ•˜๋Š” ๊ฐ•๋ ฅํ•œ ๋„๊ตฌ๋กœ์„œ, ์ฃผ๋กœ ์‹œ์Šคํ…œ ๊ด€๋ฆฌ์ž๋‚˜ ํ”„๋กœ๊ทธ๋ž˜๋จธ, ๋ณด์•ˆ ์ „๋ฌธ๊ฐ€ ๋ฐ ์—”์ง€๋‹ˆ์–ด๊ฐ€ ์‚ฌ์šฉํ•œ๋‹ค. 4. ์ง„์ˆ˜ ์„ค์ •์„ '10'์œผ๋กœ ๋ณ€๊ฒฝํ•œ ๋’ค, ์ด๋ฏธ์ง€์˜ ์„ธ๋กœ ํฌ๊ธฐ๋ฅผ ๊ฐ€๋กœ์™€ ๋™์ผํ•˜๊ฒŒ ์กฐ์ • ํŒŒ๋ž‘ ๋ถ€๋ถ„ ๋นจ๊ฐ• ๋ถ€๋ถ„ 00 00 02 00 (10์ง„์ˆ˜) 00 00 0.. 2023. 8. 20.