An Overview of Virus and Malware types

A virus is a file written with the sole intention of doing harm, or for criminal activity. Viruses may harm a computer system's performance or data. Some are noticeable to the computer user, but many run in the background, unnoticed by the user.

Viruses and spyware are types of malware (short for 'mailcious software), which also includes rootkits, adware and scareware.

There is more than one type of virus, and confusingly, some are more than one type:

  • A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks (the internet is one big network).
  • A Trojan Horse (or simply ‘Trojan’) is a program that appears harmless but hides malicious functions or other software inside - like the Trojan Horse of Greek mythology.
  • A rootkit is a stealthy type of software designed to hide the existence of certain processes or programs from normal methods of detection.Rootkit detection is difficult because a rootkit may be able to subvert the software that is intended to find it. Removal can be complicated or practically impossible, especially in cases where the rootkit resides in the kernel (main system files) of the computer's Operating System. Reinstallation of the Operating System may be the only available solution to the problem. When dealing with firmware (hardware) rootkits, removal may require hardware replacement, or specialized equipment. These are particularly nasty.
  • Adware is a form of malware which presents unwanted advertisements to the user of a computer. The advertisements produced by adware are sometimes in the form of a pop-up window. Adware that observes the computer user's activities without their consent and reports it to the software's author is called spyware
  • Spyware is a type of virus that is specifically designed to steal information about your activity on your computer. Spyware writers have a number of different objectives, mainly fraudulent financial gain. Spyware can perform a number of illicit functions, from creating pop up advertisements to stealing your bank login details by taking screen shots of the sites you visit and even logging the keys you type. All types of virus may be self-replicating.
  • Scareware comprises several classes of ransomware or scam software with malicious payloads, usually of limited or no benefit, that are sold to consumers via certain unethical marketing practices. Some forms of spyware and adware also use scareware tactics. For example one method of scareware used by cyber crooks involves convincing users that a virus has infected their computer, then suggesting that they download (and pay for) fake antivirus software to remove it. Usually the virus is entirely fictional and the software is non-functional or malware itself.

So .. potentially, a virus could arrive on your computer in the form of a Trojan, it could replicate itself before moving on to another computer (a worm) and also be designed as a piece of spyware.  

How do I get a virus?

Even the most careful of computer users can get caught out and infect their device by accident.

With the current viruses changing day to day the AntiVirus companeis ar always playing catch up to keep their products capable of recognisingb the signature of the virus and protecting against it.

Viruses and spyware can get to your computer by any of the means listed below:

  •  Opening infected email attachments such as .exe files.
  •  Opening infected files from web-based digital file delivery companies (for example YouSendIt, Dropbox etc.)
  •  Visiting corrupt websites.
  •  Via the internet, undetected by the user (worms are an example of this).
  •  Macros in application documents (word processing, spreadsheets etc).
  •  USB connected devices (eg memory sticks, external hard drives, MP3 players).
  •  CDs/DVDs.

What does Ant-Virus software do?

Think of Anti-virus software as a guard watching over the files and emails that come in and go out of your computer - looking out for ones that want to do something that you don't want them to and locking them into a vault after telling you that it has an infection..

Thousands of new viruses are detected every year, to say nothing of the variants of new and existing ones. Each has a set of characteristics or ‘signatures’ that enable antivirus software manufacturers to detect them and produce suitable updates.

I cannot say often enough that it is vital to keep your antivirus software up to date in order to provide the most complete protection. While an up-to-date antivirus software package cannot protect against all malicious code, for most users it remains the best first-line of defense against malicious code attacks.

Many antivirus packages support automatic updates of virus definitions. I recommend using these automatic updates when available.

There are plenty of free virus protection suites available from the major internet security companies. In most cases, these free products are no-frills versions of purchasable products which the manufacturer hopes you will upgrade to in the future. The protection factor is likely to be equivalent to the paid-for version, but there may be limited or no technical support and some reduced functionality.

Using one of these should ensure protection against even the latest virus threats. I have provided a list of the most popular on the links page - or you could compare them for yourself at

How it works

Antivirus software scans for viruses in a number of different ways:

  • It scans incoming emails for attached viruses.
  • It monitors files as they are opened or created to make sure they are not infected.
  • It performs periodic scans of the files on your computer if it is configured to do so
  • Some antivirus software also scans USB connected devices (eg memory sticks, external hard drives, MP3 players), as they are connecting.

Some also highlight suspect websites and may have browser add-on toolbars which reference a database of known corrupt websites..

Antivirus software will not protect you against:

  • Spam.
  • Any kind of fraud or criminal activity online not initiated by a virus.
  • A hacker trying break into your computer over the internet.
  • It is not effective if it is switched off or doesn't have the latest updates with the latest virus signatures.

As I have said over and again throughout this site - the best protection is you! Stay vigilant, keep your device up to date with the lastest versions of Anti-virus and application updates - and most of all - think before you click.