Viruses? Sometimes, yes. They mostly "peaked" in the mid-90s, though, and declined as more users started downloading software online instead of trading it with friends.

Malware? No, not really. Windows spyware only really started ramping up in the early 2000s, by which point classic Mac OS was already on the way out. I'm not aware of any significant malware for the platform.

> * declined as more users started downloading software online instead of trading it with friends.*

Geez, that's counterintuitive.

Most of the common Mac viruses were executable infectors. They spread (past tense) through software sharing -- running an infected application would infect your system, causing it to spread the infection to any applications you launched.

This lifecycle depended on having some way for those infected executables to get run by uninfected users. That was where personal software trading came into the picture.

Anyways, as more users started downloading software instead of trading it, that cycle broke. The big shareware sites like Info-Mac would only accepted software from authors, not from users, and would run virus scans on anything they published anyways.

No so much, software was generally obtained straight from the vendor's site, often legally. Although piracy existed, there was some sort of honor culture around the Mac.

Most of us Mac users can thank lone wolf developer John Norstad for protecting us:

http://www.norstad.org/disinfectant-retire.txt

Of course hilariously enough he retired Disinfectant after the onslaught of Microsoft macro viruses/malware.