What Is a Trojan Horse?

One of history’s great literary classics is Homer’s Iliad, which tells the story of the Trojan horse—the wooden horse that the Greeks hid in to enter the city of Troy and take it over. Two thousand and some odd years later, hackers use a digital Trojan horse to hide malicious files in seemingly harmless files with the intent to attack or take over your device. A Trojan horse (or Trojan) is one of the most common and dangerous types of threats that can infect your computer or mobile device. Trojans are usually disguised as benign or useful software that you download from the Internet, but they actually carry malicious code designed to do harm—thus their name.

There are a variety of types of Trojans, many of which can launch sophisticated and clever attacks. Here are some types to be aware of:

• Password-stealing Trojans—These look for saved passwords on your computer and email them to the hackers. Some can even steal passwords cached in your browser history.

• Remote access Trojans—These are quite common, allowing the attacker to take control of your computer and access all of your files. The hacker could potentially even access your online banking and credit card sites if you have your password stored in your browser memory or on your computer.

• Destructive Trojans—These Trojans destroy and delete files from your computer

• Antivirus killers—These Trojans detect and kill your antivirus and firewall programs to give the attacker easier access to your computer

A Trojan can have one or multiple destructive uses—that is what makes them so dangerous. It’s also important to realize that unlike viruses, Trojans are not self-replicating and are only spread by users who mistakenly download them, usually from an email attachment or by visiting an infected site.

Here are some steps you can take to avoid downloading a Trojan horse:

• Beware of suspicious emails. Don’t open an email attachment if you don’t recognize the sender of the email
• Use comprehensive security software. Protect all your devices with McAfee LiveSafe™ service as well as stay protected from spam, sketchy files, and viruses
• Separate the good from the bad. Use an email program with a built-in spam filter to decrease the chance of a malicious email getting into your inbox
• Know the threats. Keep current on the latest threats so you know what to look for when you receive suspicious emails

Remember that Trojans are common because they are so successful. Hackers use social engineering techniques, such as mentioning a current news topic or popular celebrity, to get you to click on their email. Just being aware of what they are and how they work can prevent you from having to deal with financial loss, identity theft, damage to your computer, and significant downtime.