Trojans and Other Malware in Computing

Trojans are a common but damaging form of malware

A digital illustration of a trojan horse atop a USB flash drive

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A trojan in computing is malicious code hidden within software or data that is designed to compromise security, execute disruptive or damaging commands, or allow improper access to computers, networks, and electronic systems. 

Trojans are similar to worms and viruses, but trojans do not replicate themselves or seek to infect other systems once installed on a computer.

How Trojans Work

Trojans can work in a variety of ways. A trojan gets its name by fooling the user into thinking it is legitimate safe software, but once installed it takes control of all or part of your computer. A trojan might access personal information stored locally on a home or business computers and send the data to a remote party via the internet.

Trojans may also serve as a "backdoor" application, opening network ports, allowing other network applications to access the computer.

Trojans are also capable of launching Denial of Service (DoS) attacks, which can cripple websites and online services by flooding servers with requests, causing them to shut down. 

How to Protect Against Trojans

A combination of firewalls and antivirus software will help protect networks and computers from trojans and other malware. Antivirus software must be kept up-to-date for it to provide the most protection possible, as trojans, worms, viruses, and other malware are continually being created and changed to adapt to security and exploit weaknesses in systems.

Installing security patches and updates for operating systems on computers and devices is also critical to protecting yourself against trojans and other malware. Security patches often fix weaknesses in system software that has been discovered, sometimes after the weakness has already been exploited on other systems. By updating your system regularly, you ensure your system doesn't fall victim to the malware that can still be circulating.

Also, be aware that malware can be deceptive. There are viruses that can trick you into giving away your personal information, scamming you into sending money (such as with the so-called "FBI virus") and even extorting money from you by locking your system or encrypting its data (known as ransomware). 

Removing Viruses and Malware

If your system is infected, the first thing to do is to run up-to-date antivirus software. This can quarantine and remove malware that is known. Here's a guide on how to properly scan your computer for malware.

When you run an antivirus program and it discovers suspicious items, you may be asked to clean, quarantine or delete the item. 

From there, you'll need to remove the virus when your computer won't work.

Other types of malware infections include adware and spyware. Check out our tips for removing infections by adware or spyware for more information.