Blog spammers versus Spam bloggers

SophosLabs has been monitoring some blog spammers. While trudging through the logs of the monitoring tool we saw a number of cases where the spammers would spam links to other blogs. These other blogs had also been spammed.


Why? It is an idea used in SEO and is known as link-exchange. Basically, people link to other sites to boost their own and the others PageRank.

This technique is known as Blog spamming (where spammers spam existing blogs) and it relies on the spammer creating links (on blogs) to their target site. Spam bloggers, on the other hand, rely on free blog hosts to create link exchanges. The spammer will create a new free blog and you will get a link farm. From the link farm they will have a several links to their target site.

How interlinked are their pages? Below is an example of one such link farm.

Graph of spam

Each node in the above graph is a particular domain. The directional edges represent links between domains. The nodes around the circle are highly interlinked with other nodes which is an example of such link farm (average degree of each node ~ 4).

The site highlighted in red is one of the targets of this SEO campaign – note the number of links referenced to this site is relatively high (average incoming degree of each node ~ 2.04, while this node has 7 incoming edges).

The color denotes the popularity of the site based on PageRank – the greener the color , the higher popularity.

One of the links from the target site (a 1 pixel image callback) references a website about SEO techniques for blogs.

SophosLabs have seen SEO techniques related to Zlob campaign. The link structure used was much simpler than this intricate link farm – however, we expect the Zlob author to try something more sophisticated.