solver.py

import hashlib

from Crypto.Cipher import AES

f = open("index.dat", "rb")
f.seek(10)
ctext = f.read(5)
f.close()

# hardcoded IV found at address 0x004277f6
IV = bytes.fromhex("9C6177555316469389520095098AB8FE")

def check(pwd):
    # password is in UCS2, including the last zero symbol
    pwd2 = bytearray()
    for c in pwd:
        pwd2 += bytes([c, 0])
        
    pwd2 += bytes([0, 0])
    
    key = hashlib.md5(pwd2).digest()
    
    ptext = AES.new(key, AES.MODE_CFB, IV, segment_size=128).decrypt(ctext)
    
    # comparison function at address 0x00429de1
    if ptext == b"CLIDX":
        print("FOUND!!!", pwd)
        exit()

pwd = b"C3p@lR3c0rdings"

# replace chars
for i in range(len(pwd)):
    for j in range(256):
        pwd2 = pwd[:i] + bytes([j]) + pwd[i+1:]
        check(pwd2)

# insert chars chars
for i in range(len(pwd)+1):
    for j in range(256):
        pwd2 = pwd[:i] + bytes([j]) + pwd[i:]
        check(pwd2)