I getting strange subdomain backlinks, any idea?

Hi!

I bought a site on flippa 6 months ago, and at Majestic SEO I getting some new "backlinks" weekly to subdomains that didn't existing. I have no subdomains. But getting backlinks pointing to

flowers.mysite.com
world-cup.mysite.com
any-word.mysite.com ...etc

The seller didn't resposive, so I got no clue. Anybody has any idea why this is happening and how can I stop this? Is it bad for SEO? It looks suspicious for me, don't wan't to be slapped because of this. Any help would be appreciated!

Anybody? any idea??

Is it a WP network?
I would start with password, look for dirty script then drop exact subs via FTP
Through wrenches.
.htaccess clean?

Odds are the seller wanted a lot of exact matches in the URL... Google treats subdomains like pages so it probably helped them boost the domain stats and value on those various domain stats sites.

less likely would be a negative SEO attack that exploits misconfigured DNS:

If all the host names go to your homepage then you are at risk. If they give a 404 error then you are safe.

This could be a negative SEO attack... if you can configure your DNS to not allow wild card domains... if you cant then use canonical tags on every page and redirect 404 requests to an error page and NOT the homepage.

The way the attacks works is to trick google into thinking your site has duplicate content issues. Then they backlink to the alternate URLs so the official URLs fall out of the SERPs for not being the highest PR copies... then they remove the backlinks and you've been taken out of the SERPs... This typically only works with low PR pages because of the link building requirements.

The other way this hurts is that all the hostnames going to the same server can create a ton of server load from bots... they just keep submitting imaginary hosts to all the bots and eventually it becomes a DOS attack.

Thanks for the answers. Its a simple worpress site with syndicated news without any subdomains. I never do any link building yet.

These subdomains not exist. These backlinks look like this: keyword.mysite/sto.php/keyword +something .html
ex: travel-switzerland.mysite.com/sto.php/travel-switzerland-austria.html
bedroom-furniture.mysite.com/sto.php/white-bedroom-furniture.html

These links point to 404 becasue my site doesn't contain these articles for real, but the subdomains: keyword.mysite.com point to my homepage. I have no idea how to get a rid of it. Links coming from different high PR forum comments with long spunned comments, and at the end of the comments there are 2-5 links to my site (with these different subdomains) and to some other sites. Comments placed between 2005-2008, long ago before the domain was registered by the seller (2012). This links looks made in the past (for negative seo), but Majestic SEO is still discover new ones on daily basis. How to configure DNS? Is it help? Almost all of my pages indexed by google, getting daily 10-20 organic visits...so I don't know is it affecting my site or not. But I want to be safe from this...

Thanks in advance