Has anyone ever seen this before?

Found a 404 error in GA this morning. Clicked to see what link it was coming from...to decide whether to redirect or not.

Was an 'outside' page linking to my site with an invalid product code. Immediately, my scanning service detected a trojan with malicious code. Fortunately, deleted and cleaned immediately.

I've already marked the link as 'fixed' but in retrospect is there someplace I'm supposed to report a web page with a trojan if this happens again? With the quick glance I got, appeared to be a Canadian 'search engine' page with a wikipedia type set up.