Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
See these Apple articles:
If you require anti-virus protection I recommend using ClamXav.
david napolitano wrote:
I'm worried that joining it may have opened my Mac to being infected with malware or spyware -- could this happen?
Only if you had the firewall turned off or sharing turned on. Even then, it's unlikely that anything placed there was OS X compatible unless you are at a Mac conference.
Most A-V software won't detect Mac spyware since it almost always requires physical access to your computer. MacScan from SecureMac does, but it's prone to false alarms so make certain anything it identifies is actually malware / spyware and it's not very good at detecting other types of malware.
No, this would not result in you being infected with anything. Even on a malicious network, you can't just be infected by something invisibly. The greater danger is that you could have all your network traffic captured, including any passwords that are sent in clear-text (which, unfortunately, too many e-mail systems still do), and you could be redirected to malicious (probably phishing) sites when browsing the web. It would not be a bad idea to change the passwords on any accounts, e-mail or other, that you accessed while connected to that network.
If you actually downloaded and installed some software while on the malicious network, there's a very remote possibility that you could have been redirected to a malicious download. But it's unlikely in the extreme that the person who set up the malicious network would have known in advance what you might want to download, unless there is some software you needed to download as part of the conference and that someone could have known in advance that many people attending would want to download while at the conference.
If you were notified of updates while on that network and installed them, that's a bigger danger. Such networks have been known to distribute malware disguised as updates, tricking the computer into downloading them from a malicious server.