Thanks to http://www.mactips.info for this information - Reposted from http://www.mactips.info/2013/08/how-to-avoid-or-remove-mac-defender-malware-in-mac-os-x-v10-6-or-earlier
A phishing scam has targeted Mac users by taking them from safe websites to fake websites which tells them that their computer is full of viruses. The user is then offered Mac Defender “anti-virus” software to solve the issue.
Be careful because this “anti-virus” software is malware (or malicious software). The only purpose they made this program, is to get the user’s credit card information which may be used for disingenuous purposes. The most common names for this malware are MacDefender, MacProtector and MacSecurity.
Apple released a free software update (Security Update 2011-003) that will help to find and remove Mac Defender malware and any suspicions program automatically. We will also provide you with some solutions and step-by-step instructions on how to avoid or manually remove this malware throughout the article.
If any notifications about viruses, antivirus or security software appear on your browser. If the normal quit from the browser doesn’t work, then Force Quit the browser. If your browser automatically download his malicious software, cancel the installation process quickly.
If the malware has been installed, don’t enter your credit card information under any circumstances and follow this steps:
- Close the Scan Window.
- Launch Activity Monitor from the utilities folder in the Applications folder.
- Pick All Processes from the pop up menu in the upper right corner of the window.
- In the name column, look for the name of the app and select it (names include: MacDefender, MacSecurity or MacProtector.)
- Select quit from the Quit Process button in the upper left corner of the window and Quit Activity Monitor application.
- Open the Applications folder.
- Locate the app ex. MacDefender, MacSecurity, MacProtector or other name.
- Drag it to the Trash
