Fun With Packets!

Firstly, I need to be clear that this exploit has been patched!
Because of the extremely detrimental nature of this exploit I never shared it with anyone except for the GM I reported it to when I quit a few weeks ago and one friend, earlier today, to confirm that it has been patched.

Basically what I found was that when using the Garden Strongbox in your Mog Garden the server validation was flawed.
The client would check:
"amount in box" >= "amount removed"
But the server would only check:
"amount in box" != 0

The server sends a 0x034 type packet with information about the menu that's displayed when you select you Garden Strongbox. This packet contains parameters telling the client how much gil you have in your Garden Strongbox. So just replacing that parameter with a larger value allows you to bypass the client side check. Since the server does check that the amount in your box is not zero you do have to put some amount of gil in initially but then it would gladly give you however much gil you requested. This puts your Strongbox into the negatives which would still pass the != 0 check. The dialog box only allows you to type in numbers as large as 99,999,999 but you could just continue to pull out that much until you had capped gil, then go spend it and do it again.

The one catch was that now your Garden Strongbox would have a negative amount of gil in it. All a GM had to do was check your box and you're done for. Although you could always put all the gil you took back in the box to restore it and there would most likely be no record.

Here's the code and a video I made when I first discovered it: mega

It's obviously of no use now but I found it funny/interesting and wanted to share :)