Your site can be hacked by others or compromised by you. There is little you can do to prevent hacking. Even large, secure sites fall victim to professional hackers.
Download the site to your computer periodically. We suggest doing that for numerous reasons:
1. To scan your site for viruses. It is relatively easy once you have downloaded it.
2. If your site has been compromised it is safer and faster to use your own backup files.
3. If your site is hacked and you have a recent backup you can replace the entire site in a short amount of time with the copy you have.
4. If your host runs into trouble you can upload your backup with another host and be up and running as soon as you have moved your domain.
Check your code. Is there any code on the page that you do not recognize? If you did not write it get rid of it. (Of course be ready to undo everything you do in case you accidentally get rid of necessary codes)
The only new code you might find and want to leave is a meta tag Google writes on the home page.
Look at the modification dates. Did you modify the sites on those days? Usually the modification dates change when a site is hacked. If you did not save the site on the modification date, it could mean trouble.
Is your site badware?
If your site has been hacked it may be infected.
If you link to sites that contain badware Google considers your site just as bad. Before linking to a site check the StopBadware.org badware list. Avoid any sites that are on their list.
The badware police
Google and the public report any signs of badware to StopBadware.org. (This includes all sites linked to badware)
StopBadware.org then checks the site. If they confirm badware or links to badware the site is added to their database. Any site in the database is then flagged by Google as dangerous. Anyone finding the site through Google is warned to stay away.
Unfortunately there is no distinction between sites that have been hacked and sites that are designed to be malicious. Also there is no indication of which sites have been visited and found safe. One cannot assume that a site not flagged is safe. Since it can take over a month to get a site off the badware list, you cannot be sure that a flagged site is still dangerous.
There are about 40,000 sites on their list at the present time. Considering their criteria we think that there may be ten times that many badware sites.
McAffe Site Secure McAffe is also scanning the Internet. Once their software is installed on a customer's computer a detailed report is available on sites that have been inspected. Sites they have not inspected are marked accordingly.
Check to see if your site has been visited. If not, submit it for a review. Use it to check any site you are considering linking to. Do not link to a site market unsafe.