Links being added to my index html file

my index file is propagating itself with numerous links

[Cando]

Hello,

I have domain that currently does not have a web site built on it, so I use a blank index html file to prevent my directory from being listed if someone should type the my domain in their browser.

I just recently noticed that my index file was propagating itself with numerous links, like this:
===========================================
<!-- google --><font style="position: absolute;overflow: hidden;height: 0;width: 0">
xeex83012
<a href=http://example.com/[directories]/placename.php>placename</a>
<a href=http://example.com/[directories]/pond.php>pond</a>
<a href=http://example.com/[directories]/theo.php>theo</a>
<a href=http://example.com/[directories]/brushing.php>brushing</a>
<a href=http://example.com/[directories]/roadmate.php>roadmate</a>
a href=http://www.example.net/[directories]/bennet.php>bennet</a>
<a href=http://www.example.net/[directories]/juice.php>juice</a>
<a href=http://www.example.net/[directories]/wii.php>wii</a>
<a href=http://example.org/[directories]/poweredge.php>poweredge</a>
<a href=http://example.org/[directories]/bayer.php>bayer</a>
<a href=http://example.org/[directories]/surgeon.php>surgeon</a>
<a href=http://example.org/[directories]/clare.php>clare</a>
<a href=http://example.org/[directories]/ge.php>ge</a>
</font><!-- google -->

===============================================

Now the above is just a small sample of the links, and these links were all created overnite. For yesterday when I first noticed this, I deleted the index html file and uploaded another blank index html file ... and then changed my cpanel log-in passwords. Only to find the file populated once again this morning.

Does anyone know what might being going on here and how I might prevent this from continuing?

Thanks in advance,
Cando

[edited by: tedster at 2:26 am (utc) on Dec. 31, 2009]
[edit reason] replace dangerous domains with "example" [/edit]

[tedster]

Your server has been hacked. You need to fix that (update your software with the most recent patches, at the very least) or your domain will continue to be hacked for what is called "parasite hosting" of links to spammer sites and malware downloads.

[ogletree]

Also check your permissions. If you have the wrong permissions they can do that.

[phranque]

it is also possible that if you are on a shared server there are vulnerabilities caused by an insecure environment.

[Cando]

Thank you everyone, I believe I have solved the problem, as I haven't had any occurrences since making some changes on Dec 30th :-)

Thanks again for your help!

Oh and my apologies tedster, for posting possible "dangerous" links, (never thought about that) and for editing them for me.

Cando