- Virus. A virus infects your computer without your knowledge or any action on your part. Viruses often do damage to your computer files or cause it to behave in unwanted ways such as taking over your web browser and redirecting any website you try to visit to an undesirable website of their choosing. To this day, there are no documented cases of a true virus for the Mac.
- Trojan horse. A trojan horse is app that you download that claims to do something you want and instead does something bad to your Mac. Trojan horses attempt to trick the user into downloading them.
- Malware. Malware is a general term for anything bad finds its way on to your computer.
- Phishing. Phishing is the attempt to fool the user into thinking they are visiting a legitimate website when you are really at a website that is attempting to steal your private information. Learn more about phishing from these tips.
You become infected with MAC Defender by visiting a special "poisoned " website that downloads Mac Defender when the page loads.
If your Mac become infected with MAC Defender it tries to fool you with phishing. It will pop up a window where it pretends to scan your Mac for viruses. After the fake scan, you are told that you do in fact have a virus and MAC Defender will remove it for you if you buy their software. You are asked for your credit card and other personal information. There is no virus and there is no virus removal software. Mac Defender's sole purpose is to steal your credit card information.
Mac Defender has changed in two ways in the past couple of weeks to make it harder to avoid:
- It no longer requires an admin password to install. It quietly installs itself.
- The creators have manipulated the search engines to make the "poisoned" websites look more legit to trick you into visiting them. The poisoned websites aren't just the "shady" web destination that they were before.
- MAC Defender cannot damage your Mac or its files in any way. Its sole purpose is to steal your personal information.
- MAC Defender is unable to poison legitimate websites like Amazon, Google, Yahoo!, Chase, etc. The poisoned websites are created by MAC Defender's creators. Granted, these websites are designed to trick you into thinking they are legit sites, so be careful when visiting websites you've never heard of.
- If your Mac becomes infected with MAC Defender, it is very easy to get rid of. Apple has posted removal instructions here.
- Mac OS X never offers to scan your Mac for viruses and never sends you to a third party like MAC Defender to buy removal software. If you see such a thing, you are being scammed.
- The answer to the question "Should I have antivirus software on my Mac?" seems to be changing from "no" to "probably not". (See the last paragraph of this article.)
If there are further developments, I will update you again.