Built-in anti-virus program?

See this on how to remove MacKeeper:

http://applehelpwriter.com/2011/09/21/how-to-uninstall-mackeeper-malware/

You made a good call by uninstalling MacKeeper, it's bad news 😉.

You could also download EasyFind and search anything that says MacKeeper or Zeobit and trash it and also check there are is nothing MacKeeper listed in your startup items.

Your iMac doesn't have a built in anti-virus program. It does have a built in firewall. Check that it's enabled by looking at System Preferences, Security and Privacy pane. Also, while there, click on advanced to ensure 'enable stealth mode' is checked.

There have been and will be, many discussions about the value of an anti-virus program in a mac. Since you can search for those if interested, I'll just mention if you want an anti-virus program, most agree that http://www.clamxav.com is the one program to use.

MacKeeper is highly invasive malware* that can de-stablize your operating system. It is also unethically marketed and a rip-off.

Further opinion on it and how to uninstall MacKeeper malware:

http://applehelpwriter.com/2011/09/21/how-to-uninstall-mackeeper-malware/

Do NOT download or use the ‘MacKeeper uninstaller’ from the Zeobit site, as this will cause even more damage to your operating system.

This is also worth reading:

http://www.reedcorner.net/news.php/?p=245

Equally phoney is iAntivirus:

http://www.reedcorner.net/news.php/?p=341

* The expression ‘malware’ is a general term used by computer professionals to mean a variety of forms of hostile, intrusive, or annoying software.

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

https://discussions.apple.com/docs/DOC-2435

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

Bear in mind that from April to December 2011 there were only 58 attempted security threats to the Mac - a mere fraction compared to Windows malware:

http://www.f-secure.com/weblog/archives/00002300.html

(I have ClamXav set to scan incoming emails, but nothing else.)

BGreg wrote: Your iMac doesn't have a built in anti-virus program.

I realize it's limited, but what about XProtect?

I realize it's limited, but what about XProtect?

If we include malware in the definition of anti-virus, then, good point, my statement was too broad. XProtect is built into OS X to address malware, which is updated by Apple.

BGreg wrote:

XProtect is built into OS X to address malware, which is updated by Apple.

There is also the quarantine system which reminds you to think before launching something that was newly obtained from the internet and which XProtect uses as a queue to check for malware as well as an option to use Google's Safe Browsing protection in Safari (and other browsers) against known dangerous web sites. What it doesn't have is any type of on-demand scan capability under user control to check for things that might have been seeded before XProtect, arrived before XProtect definitions were updated or somehow slipped onto your hard drive through some process not covered by those systems.