If you are trying to monetize your website with contextual advertising chances are that sooner or later you will come across Clicksor. If you do, my advise to STAY AWAY if you do not want to compromise your website!

I have been testing their system on several of my websites for the past few weeks and found some very disturbing things. In particular the strange behavior of certain ads.

Many visitors to one of my website, including myself, were greeted with the following pop-up (you may need to click on the image to see it full size):

Initially I thought that the website was hacked. But after closer examination and testing I have discovered that pop-ups were associated with Clicksor ads. In the process of testing I was able to take few screen shots which may help you do avoid installing unwelcomed software on your computer.

If you click “cancel” button to close the pop-up chances are that the web page that you are looking at will display following (unclickable) ad:

If you decide to close the pop-up with your are very likely to see following pop-ups (click on the image to view it full size):

At this point these pop-ups are just a set of fake cover-up and the Drive Cleaner is most likely installed on your computer. Make sure to run a software that can remove this program.

I have e-mailed Clicksor about the problem few days ago, but still am waiting for an answer. I am not a security expert, and this so called Drive Cleaner may not pose a big security risk to your computer, I am upheld at such a loophole at Clicksor. In my e-mail to Clicksor I have mentioned that these kind of ads compromise both Clicksor and their publishers. So after this post I am canceling account with Clicksor and would advise every one else to stay away from them. I will also forward the link to this post to Clicksor, maybe they will have an explanation about the issue.

If you are using Clicksor ads on your website and are experiencing similar probem, taking down the Clicksor code from you pages will eliminate the problem.