Some spam messages also simply contain tags and hyperlinks intended to boost search engine ranking rather than target human readers.
Most forum spam consists of links to external sites with the dual goals of increasing search engine visibility in highly competitive advertising domains such as weight loss, pharmaceuticals, gambling, pornography, real estate or loans, and generating more traffic for these commercial websites.
The link sits quietly in the signature field, where it is more likely to be harvested by search engine spiders than discovered by forum administrators and moderators.
Since November 2006, a very destructive forum and wiki spam attack has been propagated by inserting into comments redirect domains with an automated posting script like XRumer.
If a user clicks on the image or attempts to close the Website an ActiveX codec will be downloaded as a Zlob Trojan.