CMIYC2017 - Challenge8 vBulletin
I play a bit with the CMIYC2017-Contest. In this Challenge are some vBulletin-Hashes (challenge 8, mode 2711). Six with normal Salt-length (lenght 30 and all cracked) and the Rest with Saltlength of 30+. I tought i shorten the Salt to 30 and shift it, but i have no Result. 
I cheat  a bit and look in the CMIYC2017WriteupHashcat from the hashcat-Team. There i read, that the vBulletin salts were truncated at length 29. I dont understand this. Why is it truncated to 29? Normal length for vBulletin is 30 random chr(33-126). All used Chr in the remaining salt are ok and only longer as necessary. 
How can i identify the correct Salt to build the correct Syntax for hashcat?
You just generate all possible "hashes" (with all possible salts, the characters that are normally used is well-defined) and try to crack them. Of course not all hashes will be cracked, but the number that will be crack should be equal to the number of hashes that were in the original (truncated) hash file.
thanks, I found the problem