If you host multiple sites within the same account and one of them is hacked, it is more than likely that all of them will get hacked afterwards. There're various reasons why this may happen, the two most popular are: using very weak passwords or using outdated scripts with widely known weaknesses. This way, one single compromised site can make a lot of damage to all your sites, as gaining access to one script often allows hackers to access the entire Internet hosting account. This is the reason why we've introduced an outstanding security option called JailHost. Once enabled, this option will literally lock a site within its folder, so if an attacker takes over it, the other sites in the account will remain hidden. Thus they'll be protected from further intrusion. The JailHost option doesn't suggest that you should not keep your sites updated, but it'll greatly limit the damage.
