The Google Webmasters Blog has published a checklist for webmasters to get a better idea of their site security. A quick rundown of the steps to be performed:
- Check your server configuration
- Keep on top of the latest updates and patches.
- Watch your log files.
- Ensure that common site vulnerabilities are patched.
- Be cautious of third-party content providers.
- Use the Google site: search to see what pages are indexed.
- Use Google's Webmaster Tools
- Use secure protocols (SSH, SFTP)
- Read the Google Online Security Blog
- Get support from your hosting company if necessary.
Overall, good list. Google adds that this list is a good starting point but if you're overly concerned about the security of your site, you should conduct research elsewhere as well. Alslo, good advice.
Forum discussion at DigitalPoint Forums.