In Greek mythology, Zeus is the father of all gods and men. Today in the tech world, Zeus is the father of all computer viruses. The Zeus Trojan virus, which has been around since 2007, has been described as one of the most powerful, sophisticated, and evasive viruses ever. Many antivirus programs have had difficulty defeating it. Experts believe that millions of computers may have the virus without users having noticed.

Zeus behaves like many other viruses in that it may lure the PC user into clicking an infected link in the body of an email, then instantly downloads the virus, which quietly installs itself in the background. Sometimes that link may point to an infected website, which injects the virus in the form of a “drive-by download.” Once Zeus has been installed, it works as spyware, recording keystrokes as the user types.

Last month, the FBI broke up a hacking ring that had used the Zeus virus to steal more than $70 million. More than 100 people were charged or detained, including code writers in the Ukraine and “mule-network operators” throughout the United States, the United Kingdom, and Ukraine. The ring primarily targeted U.S. bank accounts, as well as some in the U.K., the Netherlands, and Mexico.

Zeus is designed to steal bank account login credentials. It has traditionally targeted PCs, but has now been updated to attack cell phones as well, with one version of the malware apparently “intercepting SMS confirmations sent by banks to customers, and defeating the fund transfer authorization codes.”

Protect yourself from this and other viruses by running free operating system updates from Microsoft. Click “Start,” then “All Programs,” and then scroll up the menu and select “Windows Update” or “Microsoft Update.”

You should also install antivirus software. Most PCs come bundled with antivirus software that is free for the first year or six months. Just renew the license whenever it expires. Most antivirus software categorizes spyware as a virus now, but it’s also a good idea to run a spyware removal program daily. You should also install a firewall. Microsoft’s operating system has one built in, but it is not sufficient. Use a third party firewall that comes prepackaged with antivirus software.

And don’t be a fool. Scammers consider you, the target, “simple minded.” They’ll use 1001 different techniques to trick you into divulging your data. They attempt to gain your trust by lying, sending misleading emails, or planting pop-up ads that try to convince you to download software for your own protection. Just hit delete.

Robert Siciliano, personal security expert contributor to Just Ask Gemalto, discusses phishing on NBC Boston. (Disclosures)