What is a computer Virus
A computer virus is malicious code that would infect your computer. A computer virus can have the ability to delete files, change settings, eat up CPU and memory resources and can cause complete system failure. True computer viruses can only be executed via human assistance. Some of the ways they can enter and affect a computer system is via removable media, e-mail attachment, downloaded software, usually shareware applications.
There are a many forms of computer virus threats today. A Macro computer virus is one of many which are usually executed when opening a microsoft excel or word document. The computer virus would then do whatever the macro has been programmed to do such as deleting files.
Where do computer viruses come from?
Humans create computer virus threats. It’s the bad guys out there, hiding in their bedrooms with their computers, cup of tea, and an internet connection, programming and designing viruses. Motivation for them to do this can be for a number of reasons such as they have the skills to create computer virus threats and would like to cause mischief, they may be angry with former employers, boredom, making illegal money and possibly because they want their work to be on the front of all national news papers!
Types of computer viruses
Below I describe a few of the common types of computer virus threats, as well as describing the meanings and terms for Spyware and Adware.
Trojan Horse or Trojan Virus
A Trojan Horse simply looks like an innocent and legitimate program, but can be very malicious. You may install a free game downloaded from the internet, and in effect also execute a hidden trojan horse, which can open doors to your system. This would then allow hackers access to your system, which could mean passwords and confidential data theft.
A Worm Virus or Computer Worm
A Worm is also a malicious code, which unlike a computer virus can also spread to other computers filling up memory and eating up bandwidth resources. Worms do not need to attach themselves onto existing programs like computer viruses, and although worms can take part in malicious activity within a system, they are usually designed to spread and slow down IT resources making it difficult for users to access resources and decrease response times.
Malware is a term short for malicious software. These can be anything malicious such as trojans, worms, and other types of computer viruses threats and other malicious programs intended to cause harm.
This is a program which is secretly installed on a computer. Spyware usual focus is to spy on a user’s activity, such as which websites are visited. Spyware can also re-direct browsers which could lead a user to a harmful website, change a user’s home page and force pop-ups. The common intention of spyware is to attract a user into purchasing a product or service, so it’s used for marketing purposes usually.
Spyware is installed via a user’s interaction, and without their knowledge. A common example is when a pop-up is displayed saying “Your system contains so many viruses”, and asks a user to click on the scan button. This would in fact install spyware on the local system. Also installing such programs as Kazaa contain spyware.
Adware is when a program is installed without user’s knowledge and displays advertisements. Adware is usually tied in with free software over the Internet. The intent on this again is to attract users to products and services.
Spyware and adware are both very similar and used interchangeably. As well as spying on user's browsing activity and changing settings, forcing pop-ups, the other major issue with both of these threats are they have an effect on computer performance, though slowing it down.