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Avoiding the dreaded computer virus in small businesses

If you have ever experienced a virus on your personal computer, you will know how frustrating it can be. Bringing a virus into the systems of your small business could result in disastrous consequences, so it is important to takes steps to minimise the risk. The terminology used by computer security experts when referring to virus threats can be confusing and sometimes even contradictory, but these are some of the key terms and variants:

  • Malware is any type of software designed to harm a computer, breach security or otherwise carry out malicious activity.
  • Viruses and worms are both designed to spread from computer to computer. Technically speaking a virus requires human action to spread (such as forwarding an email attachment) while a worm ‘self-replicates.’
  • A Trojan horse is a piece of malware that’s disguised as a legitimate application.
  • Spyware is software that retrieves personal data from a computer and then transmits it to criminals.
  • A botnet is a network of computers infected by malware, letting criminals harness their combined computing power for activities such as attacking websites.
  • Ransomware is a form of malware that makes files on a computer inaccessible and then demands payment to unlock them.
  • Adware is a form of malware that inserts unwanted advertising when the user is looking at websites.

Anti-virus software uses two main methods to detect and remove threats. One is to compare files with a database of known malware (which is why its so important to keep anti-virus software up to date.) The other is known as heuristic analysis, which roughly translates as using a “rule of thumb.” This means the software looks for files and activity that show characteristics similar to known malware, even if it these files aren’t yet on the daabase.


You’ll normally have two main options for the anti-virus software to do its work. One is a scan of some or all of the files on your computer, which can happen automatically when you start your computer, automatically on a fixed schedule, or when you manually trigger it. The other option is live or “real-time” scanning which checks every file that’s introduced to your computer through Internet activity or removable media such as USB drives. In both cases you may have to make a trade-off between the most comprehensive scanning and the demands on your computer’s resources, which can slow it down.


As good as most anti-virus software is, it’s only an added layer of defence and should never be a substitute for smart computer behaviour from your employees.  It is important to regularly communicate the need to remain vigilant to avoid viral threats to your business. Key points to stress are:

  • not opening attachments or following links in emails from unknown senders;
  • checking with known senders if you are uncertain about anything they’ve sent you;
  • not following links on websites unless you are certain where they lead; and
  • minimizing the use of USB drives that may have been used in unsecured machines.

If you need help deciding which is the best antivirus software for your business and how to install and administer it, or in developing a security policy for your staff, get in touch with Ratcliff IT.