[Question] Site Hacked

[puertoblack2003]

good day,

I'm curious if a vbulletin board can be hacked from outside Source? Why, because i have 2 sister sites that there board was hacked from outside source not to sure what was done but i know they had to close it till they have to fix what ever damages had occured that being said what can i can i do to prevent outside source entering my board or any other board from being hacked? is there a program to stop that from happening.

also they are up to date with program.

thanks in advance