The danger is that the user with the infected computers are actually posting legitimate posts to bulletin boards, unaware that a malicious link has been slipped into the text by the trojan. So be wary of links within posts. I've added a link below to the ZDnet article.
The above may vary so please give a description in the body of a post if you are adding a link just as I did above."It inserts 'Have you seen this link?' along with a link to what seems to be a video,"
http://news.zdnet.com/2100-1009_22-6162 ... ag=nl.e550