A lot of webcams are horribly insecure by default. This doesn't mean that they should never be used; there are a lot of situations where it really doesn't matter who sees what the camera is seeing, and experts may very well get it right. A lot of people will get it wrong, however (either by misconfiguration or by insufficient security elsewhere) and Bruce Schneier wrote an entry on a Register article about a couple of cases that have made it through the UK courts recently dealing with hijacked computers and webcams.

More entertaining, however, is a link from one of Bruce Schneier's comments, back from 1999, to image captures from both the camera and the computer screen after the intruder decided to have some fun.

This obviously isn't a new problem, and it extends to things other than webcams, as Paris Hilton's continuing problems with personal privacy have been graphically demonstrating. The combination of increasingly powerful monitoring hardware, insecure infrastructure, and untrained users is leading to an erosion of privacy in general for the average person. There are, of course, laws against intrusion, but they aren't serving as sufficient deterrent — it takes, after all, only one person willing to take the risk.

The solution? Well, don't leave things on network-equipped hardware in unencrypted form unless you really don't mind if they eventually become public, and don't leave cameras or other recording devices active when you don't want something recorded. If you don't understand encryption well enough to protect your data, and don't understand your hardware well enough to know when someone might be able to turn it on remotely, stick to the simple trick of unplugging things when not in use.

(Why is it that no almost webcams come with lens caps, anyway?) [Updated to add "almost", thanks to comments about Apple's iSight. -Z]