hxp CTF 2022 hxp

2022

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secure_flag_dispenser

by kirschju
misc rev crypto

Difficulty estimate: easy - easy

Points: round(1000 ยท min(1, 10 / (9 + [15 solves]))) = 417 points

Description:

With all that recent hype about VPNs and everything good ol’ hxp had to up their crypto game, so we added network-based security to this flag dispenser. We think that–despite our age–we’re still perfectly capable of producing flawless C code, but to be extra safe, we cranked up the compiler-based defenses during compilation of the server and enabled clang’s safe stack.

Besides the server we provide captured traffic from and to that port for you to analyse, could you please check that we got it right?

Note: We did not modify the source code of the statically linked crypto library.


Download:

secure_flag_dispenser-3e953071990b9bd6.tar.xz (1.5 MiB)

Solved by:

# Team Time
secure_flag_dispenser released 2023-03-10 16:00:00 +0000 UTC
๐Ÿฅ‡ thehackerscrew 2023-03-10 19:38:16 +0000 UTC
๐Ÿฅˆ pasten 2023-03-10 21:31:54 +0000 UTC
๐Ÿฅ‰ copy 2023-03-10 23:37:46 +0000 UTC
4 Aali 2023-03-11 03:08:01 +0000 UTC
5 PLUS 2023-03-11 09:27:41 +0000 UTC
6 Kalmarunionen 2023-03-11 10:10:43 +0000 UTC
7 Blue Water 2023-03-11 11:18:30 +0000 UTC
8 Dragon Sector 2023-03-11 14:50:30 +0000 UTC
9 Zer0Tolerance 2023-03-11 18:01:36 +0000 UTC
10 ALLES! 2023-03-11 21:21:12 +0000 UTC
11 KITCTF 2023-03-11 21:25:02 +0000 UTC
12 idek 2023-03-12 10:54:48 +0000 UTC
13 r3kapig 2023-03-12 11:33:36 +0000 UTC
14 purf3ct 2023-03-12 12:16:14 +0000 UTC
15 RedRocket 2023-03-12 12:41:03 +0000 UTC