Although we are pro-active in apply fixes for network, system and software vulnerabilities, and check frequently for news of such exploits; there is always a chance that someone will use a new technique in the short period before we become aware of it or have a chance to guard against it. As long as our servers are on the Internet there will always be a chance of this, although we do have programs in place that try to proactively analyze and prevent such attacks.
Often an attempt to hack a website arises from personal malice against a particular website or user, but can also come from malevolent curiosity being applied randomly to one of our servers. We are quickly alerted when such an attack is in process, and have several means to stop it, usually quite quickly. However, a sustained or more destructive attack may take longer to remedy.
As with the possibility of file system and database corruption, we encourage our users to make regular backups of their website(s), so they can restore this data in case of corruption or - albeit a rare possibility - malicious deletion.
We also encourage users to only give their account information to those they implicitly trust (if anyone else at all), and to use caution in running others scripts and services on their websites.