This post preserves my original public notes for cr3 CTF 2024 Writeup Roundup. I kept the challenge-by-challenge structure close to the source Markdown and only cleaned up formatting, image paths, and repeated footer text so it reads cleanly on the website.

cr3 CTF 2024

Conclusion

Pwned flags: 5/47

Total Score: 154 points

Rank: 82nd

• Forensic
  • Dount
• Professional Programming and Coding
  • Spurdanity-Check
  • Spurdo-Treasures
• Misc
  • Sanitycheck
  • Survey

Donut

Do you want some donuts? I have one for you :)

Solution Strategy

ls -a

Found that they have a .git folder

tree -a 

After reviewing the Git commit history, I traced the previous changes.

/home/waaris_m/Downloads/for_donut/donut/.git/logs

git show 2a461812df0b80851da28cf6e69f3a2d84129b01

Sanitycheck

come join our discord server and find a flag there

https://discord.gg/hhh4Bk2CvX

Solution Strategy

Spurdanity-Check

In and out, 15-minute adventure.

Solution Strategy

try: input = raw_input
except NameError: pass

a, b = map(int, input().split(' '))
print(a + b)

Spurdo-Treasures

In an ancient temple, the famous bounty hunter Spurdo found a room with hidden ancient relics. Please help him to avoid traps that could be inside this room.

Solution Strategy

import math
import sys

def find_artifacts(L, R):
    C_start = math.ceil(math.sqrt(2 * L))
    C_end = math.floor(math.sqrt(2 * R))

    for C in range(C_start, C_end + 1):
        square_sum = C ** 2
        a_low = max(L, square_sum - R)
        a_high = min(R, square_sum - L)
        
        if a_low <= a_high:
            a = a_low
            b = square_sum - a
            if a != b and L <= b <= R:
                return a, b
    
    return -1, -1

def main():
    input = sys.stdin.read
    L, R = map(int, input().split())
    a, b = find_artifacts(L, R)
    print(a, b)

if __name__ == "__main__":
    main()