Level - Hard
Description:
This should be really easy, right?
[zip.zip]
The file flag.txt was zipped into zip.zip with the password password123. After brute forcing the password, you'll get the file, which says "XOR extra field with abcd". If you extract the bytes of the extra field (CD A1 CA AA 8B A4 D8 ED DF A5 CE ED C8 A2 D9 BF CE AE DF ED E8 9F E8), convert from hex, and XOR with 0xabcd, you'll get the text flag is the correct CRC. While unzipping, you'll notice that it says the CRC is wrong. At this point, just copy the correct CRC and put it in as the flag (note - many versions of the flag will be accepted).
Flag - byuctf{ad74b76d}