Thread:Project:Support desk/Search results page redirects to unsafe site/reply

It would be helpful if you provided a link to your wiki (Mostly looking through Special:Recentchanges [in particular, any edits to the mediawiki namespace] could rule out if its a compromised admin account or something else).

In theory, an admin account can add site-wide js, which could potentially be used to do something like that. However, if someone did that, there are more evil things they could do for quite a bit less effort, so that seems unlikely.

I think its more likely that someone got into your server (possibly via some other insecure web application that you had installed) and modified some of MediaWiki's php files.