Canonical tell us how their forums were compromised, with some gaps in the explanation.
" Finally, we’d like once again to apologize for the security breach, the data leak and downtime."
We don’t know how the attacker gained access to the moderator account used to start the attack.
(…)
We’ve switched to forcing HTTPS for the administrator and moderator control panels and made it optionally available everywhere else.
Well then. :>