Worm
A worm is a piece of malicious software that can prevent certain functions of your PC from taking place. The way that worms are designed mean that they run in the background so that you won’t realise that they are there until you cannot carry out a particular function such as opening a word-processing document.
Trojans
The description of this type of malware is based on the Greek legend of Helen of Troy. The city of Troy was destroyed by the Greeks leaving a huge wooden-horse as a gift to the Trojans in which part of the Greek army were hiding. As a result, the Greeks entered the city and were able to open the gates for the rest of the army. A Trojan is like a virus but it fools the PC user into thinking that it is a legitimate programme. For example, it may arrive in the form of a ‘Christmas Wishes’ email, which, naturally, you believe is ok to open. But once you have opened the mail the virus activates and wreak havoc on your PC.
Adware
Adware is free software that is subsidised by displaying adverts. So rather than you having to purchase the software, it is effectively paid for by sponsors or advertisers. Adware can do a number of things, including finding out about your online surfing and spending habits and passing that information, without your permission, to a third-party. It is claimed that this helps to channel appropriate advertisements to your PC, but you may find the windows that pop up as you use your web browser rather annoying. Adware is sometimes bundled with other software, without the user’s knowledge, or included in the fine print of an end user license agreement. Adware programs can be very difficult to remove from a user’s computer.
Spyware
Spyware covertly or secretly gathers user information and activity without the user’s knowledge. It is probably more dangerous than adware because it can record your keystrokes, history, passwords, and other confidential and private information. Spyware has been sold as spouse monitors, child monitors or surveillance tools – or simply as a tool to spy on users in order to gain unauthorised access. Spyware can be used by thieves or hackers in order to gain access to personal information such as bank or credit card details.
Rootkits
Root kits are a type of malicious software that allows a person other than the user of the PC to be able to take full control of that PC. It can be used, for example, to collect information about your PC and network and the users, or to gain access to passwords and financial details, which these days when so many people use online banking, can be extremely dangerous!
Spam
Spam is a term for sending unsolicited emails in an attempt to let people know of a particular product or service. Most spam is commercial advertising, often for prescription drugs or ‘get rich quick’ schemes. Spam can be annoying because it is unsolicited and because there is so much of it. Most antivirus packages deal with spam. The main danger with spam is that they can carry hidden files that contain a virus designed to infect an organisation’s PCs or network.
Phishing
While not strictly a virus carrying messages it is important to mention phishing. Phishing emails are fraudulent emails. For example, receiving an email from a bank or another person that may appear genuine but requests your account details and passwords. These should be ignored at all costs. Another popular scam is an email sent asking for money in order that a significant sum of money can be deposited into a bank account. Clearly this is not genuine.