Loss of traffic due to url123
 

I noticed my traffic had to half my daily visitors over night, I've been looking to find out what had caused it I thought Google might have changed to algorithm that stopped traffic getting to my site but I was wrong, I noticed that if someone found me on Google and clicked on the link it would redirect them to url123.info and pages full of ad's I found out part of the url looked like image/png;base64 and found a few links in peoples posts with this in, I know they didn't put them there, I've managed to remove all of them for now, but has anyone else had a problem with this? looking on Google it looks like VBSeo might have some exploit in it, can anyone confirm this before I but a new license