We are receiving calls and tweets to our Twitter id @netsolcares from customers who reported that their websites were defaced. We are running a scan to see if we can proactively determine if any hosting accounts are impacted. Proponents of malware and hacking commonly look for websites with vulnerabilities. These include weak passwords, third party applications that aren’t up to date or sometimes weakness could emanate from lack of updated anti-virus software on PCs. As always, Network Solutions takes these seriously and is investigating to find out how these sites were defaced.

To restore your site here are some quick instructions:

You can access backups from your Account Manager by clicking on nsHosting -> Configurations -> Website Backups. You can then restore a snapshot from a date from within the last three days.

To login to Account Manager Click Here

A large part of the preventing these events comes from users taking preventive steps such as:

Routinely change passwords including FTP/ blog/content management software
Update your blog/content management software to the latest version.
Update any plug-ins or 3rd party scripts or code you may have for your website
Update firewalls & anti-virus on your local PCs.
Make sure your file permissions are set correctly correct and do not allow unauthorized access.
This is not an exhaustive list and these incidents can happen for a number of reasons. Just cleaning it once is not enough to resolve this. You should always take precautions.

Here is a earlier blog post that has additional information Minimizing the risk of your site being hacked.A few links on the web that may be helpful to you with the caveat that we have not had the time to validate these are being provided below:
Google: Website security precautions