Blaz CTF 2024 - Ciao


Challenge

Tony, a web3 whiz, scoured blockchain transactions for hidden treasures. His diligence struck gold when he uncovered a lucrative transaction others had overlooked.

Hint: Try Sentio Explorer and see what is called!

/* Author: tonyke_bot */

# Helloworld / 193 solves / 130 pts


Solution

This is a Hello World challenge, we just only need to decode the transaction data and we can find the flag.

The format of the Flag is something like blaz{....}.

The Hexadecimal of ASCII("laz{") is 6c 61 7a 7b, so my goal is to find any possible hexadecimal associated with this string.


If we decode this call data, we’ll get another Hexadecimal.

326532393039643030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303230303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303033643637366432313230353436383635323036363663363136373230363937333230363236633631376137623537333336633633333036643635356635343330356635343638333335663730333437323734373935663465333037373566343733303330363435663463373536333662356636643436333335323764303030303030
⬇️
2e2909d00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000003d676d212054686520666c616720697320626c617a7b57336c63306d655f54305f5468335f70347274795f4e30775f473030645f4c75636b5f6d4633527d000000

The decode result can find the fragment matching 6c 61 7a 7b, so we decode again to get the Flag.

326532393039643030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303230303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303030303033643637366432313230353436383635323036363663363136373230363937333230363236633631376137623537333336633633333036643635356635343330356635343638333335663730333437323734373935663465333037373566343733303330363435663463373536333662356636643436333335323764303030303030
⬇️
2e2909d00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000003d676d212054686520666c616720697320626c617a7b57336c63306d655f54305f5468335f70347274795f4e30775f473030645f4c75636b5f6d4633527d000000
⬇️
.)    �������������������������������� �������������������������������=gm! The flag is blaz{W3lc0me_T0_Th3_p4rty_N0w_G00d_Luck_mF3R}���

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whiteberets[.]eth

Please don't OSINT me, I'd be shy. 🫣