Internet Survival Skills 104 – Viruses, Trojan Horses and Worms


Viruses, trojan horses and worms are software applications. The difference between these applications and the other programs on your computer is that they are loaded onto your computer without your knowledge or consent and generally run themselves without your knowledge.  Originally one would have had to download or otherwise transferred an executable file onto their computer and have executed it to become infected, but today we see image files, PDF’s, media files, word processing documents, email messages and web pages that can infect your system. Worms can enter a system through networks without you playing any active part in the infection.


These applications can expose files on your computer, saturate you processor and internet connection, damage your files and cripple your computer.


The best defense is to avoid infection by never downloading files from unknown sources, never opening an email attachment you were not expecting, using common sense when browsing the Internet and installing and maintaining anti-virus software.  Turning off unnecessary services, an effective firewall and keeping your operating system and applications up to date is also necessary.


An essential part of any defense strategy is to have backups of your data and your application installation media so that in the event of a catastrophe you can recover easily.


Anti-virus software is not part of your operating system. Some computer manufacturers and Internet service providers provide AV software to their customers.


While a number of firms will allow you to scan and sometimes disinfect your computer for viruses via the web at no charge, there is no substitute for continuous online protection. Microsoft and other firms like Avast and McAfee have cleaners for some specific viruses if an online scan detects an infection. These applications take the form of an ActiveX control or a downloadable executable; so make sure you are obtaining your software from a reputable source.


Symantec offers a free online security checkup as well. McAfee has a similar security assessment tool.


AVG Free Edition is for private, non-commercial, single home computer use only. The private and individual use of the AntiVir Personal Edition is free of charge.


Bit Defender offers free anti-virus products for a number of platforms


More Free Scanning Tools