Kelly here with AllClear ID. Mac ownership has been on the rise in recent years, with converts often citing their lower susceptibility to viruses as a reason for purchase. While this does have a shred of truth, it can often lead to a sense of false security among Mac owners who feel they don’t need to install anti-virus or are safe clicking on sketchy links.

However, a new Trojan has been sending the Mac community into a fury; fake installer applications are being used to trick users into downloading malware, though newer versions of the virus are being downloaded and installed without admin permission according to CNET. The Trojan horse virus, dubbed “Flashback” was originally discovered in September, but a new report by a Russian antivirus company indicates that as many as 600,000 Macs are now infected, with the majority located in the U.S. After installation, the malware locates user names and passwords stored on your computer.  Once this information is taken, hackers can use this information for a multitude of crimes – including financial identity theft.

Is my computer infected?

Unfortunately “there are no visible symptoms for this Mac virus, except for making sporadic connections to unknown servers that can be only seen in the Firewall logs, if any firewall is in place,” Boris Sharov, CEO of Doctor Web, told Mashable. Luckily, Mashable has developed scripts which allow those who are unfamiliar with command line codes to detect if their computer is infected. You can download the scripts here.

How can I prevent my computer from getting infected?

  • Turn off Safari‘s auto-open command: In Safari, go to the General section of the preferences and uncheck the option to “Open safe files after downloading.” This can prevent virus-prone executable files from being opened automatically
  • Install a malware scanner: Install a scanner like Sophos, ClamXav, or iAntiVirus, and set it up to scan your e-mail and your download folders.
  • Always be aware: Don’t fall into the trap of thinking that your Mac is immune to viruses. Be on the safe side and take the same precautions as you would with a PC.

What do I do if my computer is infected?

  • Remove the Trojan: F-Secure has provided detailed instructions on how to remove the malware from your computer if you are infected.
  • Change Your Passwords: Make sure that any information collected is useless to hackers by changing all of your passwords or user names – especially if they safeguard secure information.