The Security Mentor

Israeli police report that companies there have been bugging competitors's computers.

It was easy. They sent booby-trapped email that took advantage of security holes, or sent a CD with a business proposal and some spy software that installed itself automatically.

The people who do mass-market spying are easy to catch because they try to infect millions of computers so they can show a few dollars worth of ads on each one. Antispyware software is less likely to recognize a custom-written spy program that a dishonest private investigator plants on a few chosen computers.

There could be big money in this kind of spying. It's a safe bet that most of it is never detected, which means there's a lot more of it going on.

You can defend yourself by making it harder to install software on your computers. If you have an IT department they're probably already trying and everyone thinks they're obstructionist.

Second best is to use software like Zone Alarm that (tries to) warn you when software unexpectedly tries to send information out from your computer.