Shoutbox

Believe me, our school's IT security isn't that good.
Once they left an account with username admin and password admin on the network. It gave full access to the router (but not the server). Let alone with that, kids could have got on porn and even disabled, deleted or changed all access codes to the internet.
Secondly on the server they store all the passwords for access to the internet settings on the router in Firefox.
Their one line of defence is a virtual network control program on each computer that allows them to check what anyone is doing, unless of course they close the program which every user can without even needing to look at the processes.
They let you download .exe and .bat files, which they could easily block in their filter rules.

If I actually looked for security flaws, I'm sure I'd find a lot more. However I have no wish to do so, since all I want from the computers is an education, I don't get kicks out of "h4x0r1n" them in any way.