Q: How do I check my Mac mini for spyware and other virus

Receiving an fraudulent email confirmation for a purchase you did not make is a very common scam. Be sure that you are not deceived into providing any personal information solicited by that email.

Unfortunately, I responded by clicking on a link that invited me to cancel or manage that purchase which led me to a site that didn't look like an official Apple site. I'm concerned that, by simply doing that, I have allowed spyware onto my Mac mini's hard drive.

No harm will come from doing what you wrote. Scam websites that are made to appear like legitimate ones are specifically designed to convince you to reveal personal information. Provided you did not do that, no other action is necessary, or justified. Do not install anything, regardless of its source or apparent popularity, in response to such a scam. To do so would be the first step in a well-worn path to misery.

On the other hand, if you were deceived into providing personal information (such as your Apple ID and password) then you will need to change your Apple ID password. Please write back for instructions.

The OS X application firewall is not intended to prevent you from installing software, either intentionally or otherwise. Only you can do that, by authorizing its installation.

Merely clicking a link in an email that causes a scam webpage to load does nothing more than that. It will load just like any other webpage you might navigate to.

Some web pages will automatically start the download of some software you may not want, but even then nothing can happen unless you open and install that software. If you were to do that, OS X's Gatekeeper will provide the following dialog:

If that software wants to modify your Mac at a privileged level, you would see the following dialog:

That dialog box should never be a surprise. Only click the "Install Software" button if you are completely certain you want the software you are installing. Even then, you should have a plan for uninstalling that software in advance, in case it doesn't work or causes unexpected operation.

Provided you did not do any of those things, no other action is necessary, or justified.

The firewall's purpose is to block attempts from computers on the same network as yours from accessing ports used for various communication services. Learn about it here: OS X: About the application firewall - Apple Support. The firewall's default setting is "off".

Unless you use your Mac on a public Wi-Fi network shared by those you do not necessarily trust, don't worry about the firewall settings. Enabling the firewall will not prevent you from willfully divulging personal information, or from willfully installing software. People often confuse the application firewall with something that can protect against that threat, giving them a misplaced sense of security. That's not surprising, since the word "firewall" is an regrettably unfortunate choice of terminology for what it does. There is no fire and there is no wall.

Please read Effective defenses against malware and other threats.

Hi Politkovskaya

To check your mac if it has malwares, restart your mac and go to Safari and go to google and pretend you want to search for something you are looking for. If you are getting good results it means your browser has not been hijacked and its search engine is fine. Also if you are not noticing any pop ups after the restart then again...you are safe.

Once you encounter pop ups of applications and web sites you have never went to or you get results of searches you have never wanted to to get, then post in here what you see and I can help you further on. For now, if there is nothing wrong, you are fine.