Porn sites are not the only source of infection.
They often seem to be the source because once any spyware gets its foot in your door, it tends to invite in all its friends, and sooner or later you end up with porn links on your desktop.
There's a lot of money in advertising: an adware program may be intended to show you adverts for decent products, but then the creators of that program can bundle more spyware along with it and make money by doing so, and then these programs make money bundling other products, and all the time the spyware and adverts get more evil and sleazy.
Porn links and pop-ups are sometimes the symptom of a venal enterprise, the lowest common denominator, the last link in a chain of infection that may start with something entirely innocent.
where else could you pick up such an infection?
1) opening email attachments
2) clicking on links in spam emails
3) instant messaging file transfers
4) downloading from peer-to-peer networks
5) downloading program cracks
6) downloading phoney anti-spyware or internet cleanup products
7) even connecting to the net without a firewall or up-to-date OS and browser
Actually even malicious web sites are not particularly dangerous if your OS and browser are up-to-date: most really on ancient exploits like the MS Virtual Machine ByteVerfiy, which was patched years ago or security weaknesses in older versions of IE. Just don't fall for the social engineering of notices which say 'you have spyware, download this program' or 'download this program to clean your internet tracks', or 'you need this plug in to proceed'.
The really big dangers today are:
1) having no firewall
2) not updating your OS
3) no virus and spam filtering by ISP's
Anybody with no firewall and a OS which is out of date is going to get infected even connecting to the internet.
Anybody who doesn't have good spam and virus filtering provided by their ISP is going to have to be very careful about attachments arriving in their inbox, because these are likely to contain a new worm or virus, and if it's one that uses a rootkit, you're very likely to not even see it, and if you see it, it may be impossible to remove like for so many people who've had a FU rootkit infection.
And don't rely on an anti-virus program to catch viruses in email attachments, because even the best will not catch a new one for a few hours or even days.
A good rule is, only open email attachments if you know what it is, who sent it, and you have confirmation from them that they really did send it.
Don't be one of the people starting a thread here saying 'I have a virus and it keeps coming back' because you have been warned. If you get a FU rootkit infection then you are FU**ED. Avoid it in the first place!
