Types of Computer Virus Infections: How Viruses, Worms, and Trojans Work and Steps to Take to Protect Yourself

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As there are different kinds of infections for the human body system (viral, bacterial, etc) there are different kinds of infections for the computer system. There are three common kinds:

  • Worms basically replicate themselves on one computer using up available resources (memory, disk space) and eventually bringing the computer to a stop. These typically are spread from computer to computer through email attachments. Network worms move around from computer to computer by themselves and make copies of themselves through email, P2P, text messaging etc. These can cause idle computers to contribute to the processing of illegal workloads.
  • Viruses attach themselves to programs in a computer without changing data and run when the program is opened.
  • Trojans are deceptive. They do not ask or seek permission first. These are typically used for data theft, information theft, identity theft, distributed denial of service attacks on network servers, and as a spam platform. Their programs range from
    • recording keyboard activity (keyloggers) and sending the information to specific email addresses or websites without your knowledge or permission, to
    • controlling individual computers in a file sharing network, to
    • making your computer useless.

Don’t install any software, including anti-virus or anti-spy ware software from a link or an attachment in an email. The SpamThru Trojan gets rid of competitors in your home computer so it can be the sole sender of spam from your home computer. It pretends to be a remedy or fix for infectors. Go directly to the website of the legitimate anti-virus software manufacturer to install software updates.

The Jowspry Trojan disguises itself as ‘Windows Update’ to avoid detection by your firewall.

The Gozi Trojan avoids Secure Socket Layer protection by tricking the Windows operating system into believing it is part of the Windows process. So, when your information leaves your browser at a secure web page it goes through Gozi before it is encrypted and sent on its way. Unfortunately this happens when you are providing personal information (credit card info, password) at a secure web page when the Gozi Trojan is installed on your computer. Remember that you can recognize a secure web page by the https in the web page address or an icon of an unbroken key or lock that is closed, glowing or golden usually at the bottom of the browser window.

The Glieder Trojan begins as a small program that changes its look to avoid detection by anti-virus software. Once it is installed it will try to disable any security trying to stop it and then do its mischief. The mischief or payload can be anything the author intended from stealing your personal information to making your computer unusable.

This post is part of the series: Computer Infectors: Identifying the Infectors, Recognizing the Symptoms and How They Can Be Used

These articles explain the definition of an infector, how they can include more than viruses and worms, how to identify infectors when they first arrive so you can avoid infection and how to recognize them after they are installed through symptoms.

  1. Kinds of Computer Infections
  2. Symptoms of Computer Infections
  3. Limit the Number of Computer Infections