Referrer values are passed by web browsers and show how a page was come by. Let's say you search on Google for websites about a particular subject. If you click on a search result from a to visit a website then the destination website will have an entry in its access logs showing a referral from the originating website, Google. Referrer values can be very useful in applications such as security and are essential to webmasters as they show how their site is being linked to.

Here are some sample entries from a web access log of a website that has been spammed. From them you can see the timestamps of the visits to the site as well as the IP address of the visitor and the referrer value that was passed along with the visitor showing where the visit originated.

The most interesting website in this list is potentially www.websearchus.com as seems to be a fully functional web search engine. One could hypothesise that the spammers are using this search engine as a possible means to get innoc

ent bystanders to generate suitable spam-targets and then visit them only the referral values passed to the destination websites will be tampered with to include the likes of the above.

I visited www.a-b-l-o-g.com and viewed the source of the website to find this at the bottom of it:

 
< a href="http://www.a-b-l-o-g.com/adult-webcam/">
< img src="/adult-webcam.gif" border="0" height="24" width="78"/>< /a>

With this in mind, selecting all of the content on the webpage and then scrolling down to the bottom reveals the link in all it's glory:

Can you see the small, highlighted dot in the bottom-left hand corner of the webpage? That's the link manifestation of the HTML source code above.