Due to the recent attacks on Apple products such as Mas's and iPads to mention a few, I have decided to try and give a few tips on how you can protect yourself.
The main problem is that most people think; "Apple can't get infected with anything", and an even bigger issue is that the computer shops and malls still tells people that this is a fact. Unfortunately this is one of the main reasons why the malicious code and software can spread as fast as it does. Another problem being that you have a Mac computer and you syncronize it with your iPad, iPhone, iPod etc. thus spreading it even faster.
The more Apple products that hit the streets the more attacks we will see aimed at Apple users.
Tainted websites - Web sites have now been modified to inject malicious code into Apple products.
Mac Malware - The P2P (Peer to Peer) network is spreading pirated software that has already been injected with malicious code.
Adult Videos - Many websites will tell you that you need to install a plugin in order to view the video. Think twice before doing that because this is a very popular way to inject code into OS X.
Music - Music downloaded from the internet can be infected with a virus or trojan and if your antivirus doesn't support "on access scan" then you will install whatever is hidden on the computer!
Twitter - Links posted on Twitter will guide you to a website that is infected!
Virus Relay - You can relay a virus for Windows through your own mail application on Mac. You mac will not get infected but you send it to all your friends. Transfer of Windows viruses can also happen using iPod, iPad etc.
Windows installations - Many use a dual boot environment, where you have OS X and Windows on the same Mac. The Windows installation can still get infected and transfer information or spread viruses. Make sure that if you run a Windows installation on your Mac that you install Antivirus and a proper firewall. I recommend the free Internet Security from Comodo - www.comodo.com (use Google to search for "free internet security").
Apple has already acknowledged the problem and has released an update for Snow Leopard preventing a specific Trojan attack (Trojan - a software that appears to do something you want, but it actually implemented something else too).
OS X comes with a built in firewall and you can activate it with a simple click. To check whether your firewall is enabled or not you click System Preferences (the little Apple icon in the upper left corner), then click Security and switch to the Firewall tab.
Make sure that the Firewall says ON and if not you simple enable it by clicking Start. The application lock may be active (lower left corner) simply click it and you'll be able to change the settings. Please remember to "Lock" again once you have changed the settings.
The Firewall will pop up and ask you for permissions to run all installed applications, make sure you read the name of the application to see if it's OK or NOT. If in doubt, Google the program attempting to run.
Now what most people don't know is that OS x has a lot of communication going on, also stuff that you may not want. If you want to see how much is getting online and you want to control it you should check the small application called Little Snitch you'll be surprised at the number of popups you'll get once installed.
Unfortunately the firewall requires Terminal access and networking know-how to access all of its features.
Avast (still in beta so expect a few glitches)
Sophos Home Edition
Aobo Mac Spy Software
These are only a few of the options available. Unfortunately because we're talking about Apple products, there are very few free solutions in comparison to Windows.
Please make sure that you always update the software on your Mac. Most of the malicious software out there will disable the update function of OS X just as it disables certain parts of Windows. Very often the malicious software is capable of disabling both the firewall and any antivirus software installed.
At present there are no free online scanners for OS X!