There are two answers to that question, actually three!

Malwarebytes for Mac 10.6.8 Free Download is here http://formacos.org/malwarebytes-for-mac/.

How to prevent ads and pop-ups: Download and install GlimmerBlocker: http://glimmerblocker.org/

How to prevent re-direction:

Adding Open DNS codes to your Network Preferences, should give good results in terms of speed-up as well as added security, (including anti-phishing and redirects) (Full information about Open DNS is here: http://www.opendns.com/home/nobloat ) and further independent information can be read here:

and here:

Open System Preferences/Network. Double click on your connection type, or select it in the drop-down menu, and in the box marked 'DNS Servers' add the following two numbers:

208.67.222.222

208.67.220.220

(You can also enter them if you click on Advanced and then DNS)

Malwarebytes For Mac Cnet

Thirdly: malware!

There are many forms of ‘Malware’ that can affect a computer system, of which ‘a virus’ is but one type, ‘trojans’ another. Using the strict definition of a computer virus, no viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions. The same is not true of other forms of malware, such as Trojans. Whilst it is a fairly safe bet that your Mac will NOT be infected by a virus, it may have other security-related problem, but more likely a technical problem unrelated to any malware threat.

You may find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful:

The User Tip (which you are welcome to print out and retain for future reference) seeks to offer guidance on the main security threats and how to avoid them.

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1. Check your Downloads folder, or search your computer for the Malwarebytes setup file, Malwarebytes-Mac-4.x.x.xxx.pkg. Note that 'x.x.x.xxxx' is the version number.
2. Open the setup file by double clicking on it. If you can't open the file because it's from an unidentified developer, right click on the file and select 'Open.'
3. When the Setup Wizard opens, click 'Continue' in the bottom right to see the Malwarebytes Software License Agreement. Next, click 'Continue,' then 'Agree.'
4. Click 'Install.' Next, MacOS will ask you to authorize the download with your username and password. Type them in and click 'Install Software.'
5. When installation is complete, click 'Close' to exit the Setup Wizard.
6. Done! Malwarebytes should launch automatically.

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