I have seen some video's out there, where people enter a predefined "code" and they would get the items for free, So one hungry night,I thought to check out the vending machine to see if there was any way to get away with the food, as most of the time it would just take the money from the students and return empty.
It was time to get our money back, here is the result ;)
Stay tuned for the detailed post on how to find such logic issues and other firmware reversing. Do share if you like it and want to see more stuff's like this.
PS. This is vendor specific and won't work in all the machine's out there.