365 Computer Security Training

‘Virus’ is the most commonly uttered word in cyberspeak! But we often utter it without knowing what it actually means. Technically, a virus is a malicious program or a piece of code that is loaded onto your computer without your knowledge and runs against your wishes. They can replicate themselves and spread all over the network and into other networks by doing so.

Viruses are dangerous because they can use up all available memory or make your computer crash. An even more dangerous type of virus is one that can breach security systems and travel to other networks.

The earliest virus was the Creeper virus back in the days of the ARPANET (Advanced Research Projects Agency Network – a primitive version of the Internet) in the 1970s.

It was a self replicating program written by Bob Thomas at BBN in 1971. Creeper gained access to the DEC PDP- 10 computers running the Tenex Operating System through the ARPANET. It copied itself to the remote system where the message: “I’m the Creeper, catch me if you can…” was displayed. Later a program called the Reaper was used to delete the Creeper!

The more common type of viruses are Macro-viruses which have become common since the 1990s. Most of these viruses are written in the scripting languages of Microsoft programs, such as Office, and infected Word documents and spreadsheets.

But a virus may also be sent as a web address link over the Internet. An innocent user may think that the link is from a trusted source. And upon clicking, the virus will then execute on the system, unleashing it’s payload.  The most common way of delivering viruses to potential victims is through attachments on emails.

Once a computer has been infected by a virus, it is generally unsafe to continue using it without removing the virus and restoring it to a safe state.  In worst case scenarios it may require reinstalling the whole operating system. The System Restore option in Windows comes in handy because it restores the registry and critical system files to a previous checkpoint.