The Security Mentor

Web browsers routinely have bugs that allow malicious web pages to take over your computer. If you fall behind on installing security patches, then you're at risk from any web page that includes evil software.

The old advice used to be to avoid porn, gambling, and pirated software web sites.

Unfortunately, criminals have figured out that they can pretend to be a legitimate company that advertises on the Web, buy ad space, put a toxic payload into their ads, and then have an ad broker display malicious content for them on zillions of legitimate web pages. Brian Krebs of the Washington Post writes that high-profile sites such as MySpace and Excite were infected by malicious advertising.

Your defenses start with keeping up with security patches. After that you might consider installing the AdBlock Firefox extension into your copy of Firefox. You can use it to block almost all online advertising if you download a list of advertisers to block like Filterset.G.

I've been reluctant to block all ads, since I can put up with the non-obnoxious ones and they help keep web sites I like in business. But I may soon conclude "safety first".