VaultPress (a backup service for WordPress blogs by Automattic) has just announced a new feature for premium users which should make it harder for hackers to alter blogs undetected.

VaultPress knows which version of WordPress your site is running. For each particular version of WordPress, we know what the MD5 checksum for each of the core files should be (an MD5 checksum is a kind of digital fingerprint for a file, that can be used to validate the integrity of that file). [...]

This scan creates a baseline that we can compare against in future scans. If the MD5 checksum of a core file doesn’t match, we notify you through an alert in the security tab of your VaultPress dashboard. A variation in the checksum means that the file has been modified from the original version that came with your WordPress install. (Official VaultPress Blog)

Users who notice any suspicious changes can contact the VaultPress team who will then not only take a hard look at the core file but also help provide a remedy for you as well.

The improved security features should help separate VaultPress from less expensive rivals (like blogVault and BackupBuddy) as well as help them win a few converts (especially larger blogs who can not afford to suffer through a hack).

VaultPress’s security service is only available to premium members which is currently priced at $40/month per blog (note: this is a beta price as the final version is expected to jump to $50/month per blog), although users have to option to purchase the basic plan for $15/month per blog.

Update: Corrected article noting that VaultPress Premium will be $50/month (not $60). Thanks Paul!