Foreword This team I participated with a team of Year 4 friends of mine in NUS Greyhats. Biggest thanks to mechfrog88, davidtan0527 and DarkPermafrost for basically carrying me through this. Qualifiers A bit rough for us here. One crypto challenge got the flag leaked, hence all teams solved it. I managed to solve one misc challenge about finding the kth digit after the decimal point of a fraction a/b with a, b, k being very large integers.

Foreword I participated this time under NUS Greyhats. We did participate in the qualifiers (?) but in any case we got invited by the organizers to the finals. The finals this year is in Attack - Defense format. Setup For the tooling, we use ExploitFarm for automatic exploit and flag submission. We also use Tulip for monitoring. We have to patch two web services and two pwn services, and attack the other teams’ services also.

Qualifiers I participated in Hacktheon Sejong CTF 2023 under the c'est la vie team. The CTF this year is very guessy and do not involve high level techniques. Hence, I pretty much got carried (helped the team a bit though). The solution to the only Crypto challenge I attempted is solution with a lot of guesswork. There is another Crypto challenge, but it is in Hangul - the writing system of the Korean language, which obviously I have no idea of.

Foreword Participated in this CTF from the LiveOverflow video about this. Very interesting CTF but I only have enough time and effort to do Crypto and some Introduction to Web challenges, hence the low ranking. Crypto challenges reuse ideas from Cryptohack, so nothing really special (if you have done the CryptoHack challenges with similar ideas that is). Challenges Casino Challenge: FLAG = "CSCG{TEST}" import random rng = random.SystemRandom() # Secure group from RFC 3526 prime = int(""" FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245 E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F 83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D 670C354E 4ABC9804 F1746C08 CA18217C 32905E46 2E36CE3B E39E772C 180E8603 9B2783A2 EC07A28F B5C55DF0 6F4C52C9 DE2BCBF6 95581718 3995497C EA956AE5 15D22618 98FA0510 15728E5A 8AACAA68 FFFFFFFF FFFFFFFF""".

Foreword I participated in HackTM CTF 2023 with NUS Greyhats. We managed to get 15th place. Overall I am quite happy with my performance this CTF, I managed to solve 1 challenge solo and collaborated with mechfrog88 to solve another Crypto challenge. The Crypto challenges of this CTF are quite tough, and it is an interesting read of the solution given by the creator. I think the given writeups by the author are good enough, and should provide a better view of the educational values after solving the challenges.