STDiO 2023 Capture The Flag: 05 - Impossible Logic
The sexy hackers Christmas party requires every members to show their secret before entering the party. Each hacker has his own secret and the secret can only be used ince. Jordi was so afraid that someone will steal his access to the sexy hackers Christmas party, so he encrypted it and implemented a program to exchange key and decrypt his secret. However, Jordi was smoking weed, so he mistakenly implemented the program in the way that it will never be able to decrypt the secret. Jordi was also so high that he did not remember where he stored the source code. Help Jordi to get back his secret.
Merry Christmas ! https://www.youtube.com/watch?v=4nnYo-9B6os
Download: https://stdio-2026-public.2600.in.th/impossible-logic_x86
Author: Pgoodboy
ดาวน์โหลดไฟล์แล้วเอามาเช็คดู
$ file impossible-logic_x86
impossible-logic_x86: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=f9f34b5b7c1018fa4fa472740cbbe67413493db1, for GNU/Linux 3.2.0, not stripped
รันดู
$ ./impossible-logic_x86
Please enter your secret:
ยังไม่รู้ค้าบบบบบ แต่ “Jordi was also so high that he did not remember where he stored the source code “ ก็ decompile หาซะเลย
ใช้ Cutter ในการนี้
ใน main function -> eax = strncmp (“SmokeWeedEveryDay420”, rax, 0x14);
เทสดูซิ
Hello welcome !
STDIO23_5{dbc8baf577040ad4e6bf60a9fd9320d5}