Supermod issue

[محروم.كوم]

Hi,

We just recently installed vBulletin 3.8.6 PL1 to a subdomain on our site that was not made public. Our site just went live and we've had quite a few registrations. For some reason though, we've also seen a few 'supermoderators' being created without our knowledge. We're not sure whether this is a sign of being hacked or some sort of bug?
All three admins have changed their passwords and we've set one as undeletable but we'd like to know if there's any way to protect ourselves from a hacking attempt, if that is what we're experiencing right now?

Thanks! __DEFINE_LIKE_SHARE__