this seems to be quite serious. What I can find says there is no quick fix. best to pay them. $500!
It appears to have entered via one computer, and gotten into the shared folder because the person who got infected had that file folder open at the time. It has not spread further, as far as i can tell... that shared folder happens to live on MY computer. I unshared that folder as soon as i knew about this.... but the files that were in there my be hosed.
We're trying to isolate the location at this point.
this site is all over this... but I'm not encouraged by what I've read.