And pay the hacker no attention, do not "egg on" "challenge" or entice him/her with replies upgrade and stay current, always checking for updates to modifications including commercial third party plugins as well to avoid this in the future. Notices are sent to your admincp in regards to vBulletin, pay attention to those and mark modifications as installed on this site to receive email notices regarding updates and more pertinent information.
I hate to say this and I don't direct it at you solely however everyone needs to understand you can't simply install a forum including a few mods then let it sit and post away. You must upkeep your forum as with anything for example if it's a site you run for your business then it should be considered I dare say like a second house, beach house... you must still upkeep the house and property for regular use on vacations, you can't let it sit and not mow the grass (spam, deletion of spam, bots etc), you must setup something with the water and power company (hosting) otherwise pay monthly in order to enjoy the stay when you their, security system (updates/upgrades) then painting every few years (styles) you must upkeep your forum in the same respect I can't stress that enough

.