Malware and anti-malware software
Malware
Malware (short for 'malicious software') is a general term for any program that has been designed to attack your computer in some way. A computer can be infected by malware in a number of ways. These include via a network, by a user opening an attachment to an email, followng a link in an email and then downloading and running a malicious program, and by sharing infected storage devices.
Viruses, worms and trojan horses
A virus is a program that has been written by someone. It can replicate itself, be attached to files and applications and can cause a lot of damage because it can change the contents of your hard disk as well as use up your memory. They can spread very quickly, usually by shared storage devices or email attachments. Ideally, you should never share storage devices. You should never open an email attachment unless you know and can trust where it comes from (by checking a digital certificate, for example). Attachments to be especially careful of include file names ending in .exe .bat .pif .scr and .vbs. Other types of viruses include ‘Worms’ and ‘Trojan horses’. Worms are programs that can spread themselves via vulnerable network connections. They are standalone programs, unlike viruses, which ‘piggyback’ on other programs. In addition to unauthorised use of systems and causing damage, they can take up a lot of bandwidth as they spread and slow networks right down. A particularly nasty one called MSBlaster affected computers worldwide in August 2003. It spread very quickly, hunting for computers on the Internet without a firewall. When it found one, it jumped into the computer through the open communication port and infected it without the user knowing - until their PC closed down every time an Internet connection was made!! Another one, W32.Sobig.F@mm mails itself to all the email addresses it can find on an infected computer. Trojan horses are viruses hidden inside seemingly innocent programs. They, too, can cause major problems for your computer.
You should always have an anti-virus program on your computer and you need to ensure that the virus patterns are always up-to-date. Updating virus patterns typically happens at least once a day. An up-to-date anti-virus program will catch most viruses, worms and trojan horses most of the time.
Spyware and adware
These are both types of malicious software. Spyware is the name given to software that gets access to your computer without you knowing, often because you have downloaded and installed free software from the Internet. Spyware can gathers information silently about your computer habits and personal information and transmits them to unauthorised people. Adware is software that gets access to your computer, again usually because you have downloaded free software from the Internet or you have downloaded legitimate software but it cam bundled with adware. You often have the option to not install adware when installing any software so be careful about just clicking OK - OK - OK when installing new software! Always check to see if there is a screen that is asking if you want to install extra software that has nothing to do with the main software. Adware can cause adverts to pop up on your screen or in your browser and can add adverts to whatever browser you are using and can be very annoying.
You should frequently run software designed specifically to identify and destroy spyware and adware. Two such programs are:
and Adaware from
More about viruses
We know that a virus is a software program written by someone on a computer in a programming language and then sent across the Internet by email or spread by people sharing storage devices. They are sometimes designed to do nothing more than annoy (like making your keys beep each time you press one on your keyboard) but they often do a lot of damage such as wiping your hard drive clean or allowing your computer to be accessed by a hacker remotely or allowing a hacker to control your webcam!
You often hear people advising you not to open or double-click attachments sent with an email unless you are absolutely sure where the email came from. If you do, you might install a virus on your computer. If you are lucky, your computer will be set up to check all of your emails and any attachments you open, but a virus might still get through your computer's defences. Microsoft have identified the file extensions in the table to be a potential threat to your computer. A file extension consists of the three letters that you can see after each file name e.g. myHoliday.doc or NotVirus.exe . If you can't see the file extension in an email or in your file manager, then it is because that feature has been switched off and you need to switch it on. In Windows, you usually have to go to My Computer - Folder Options - on the View tab, remove the tick next to 'Hide file extensions for known file types' and then click on okay. It does vary between Windows operating systems but the process is similar for all of them.
There are all kinds of tricks that hackers use to try and get you to open an email attachment.
1. An email arrives telling you that your computer is infected with the latest virus in the news, and offers to remove it - all you have to do is click on the removal program attached! When you open the attachment, it disables your antivirus program and firewall. Then it installs a virus and reports to you that your computer is virus-free. The virus can then get to work.
2. Your friend sends you a file called greatGame.exe". You friends says they've played it and it's great so you open the attachment by double-clicking on it. The problem is, it contains a delayed action virus along with the game. You might get to play the game but now your computer has a virus. And all because you thought your friend knew what they were doing!
3. An email arrives that seems to come from Microsoft. The Microsoft heading and icons are correct and it looks real. The email tells you to patch your copy of Windows immediately as there is a security threat to your computer. The patch is attached to the message and as soon as you double-click it, you've disabled your firewall and anti-virus programs and installed a virus! It was a 'spoof' email, not from Microsoft.
4. Attackers can hide malicious attachments by using double extensions, e.g. "answers.txt.lnk" or "great_picture.gif.vbe". *.lnk, *.vbe and several other extensions are usually hidden. The file names you see are "answers.txt" or "great_picture.gif". When you double-click on them, you install a virus because .ink and .vbe can be used to do just that.
The above illustrates that the advice about never opening an attachment unless you really know where it came from and who sent it to you is very good advice!
Sharing storage devices
The other main way of catching a virus is by sharing back-up devices like a pen drive. When you plug someone else's pen drive into your machine, if it has a virus, it could jump from their pen drive to your computer and infect your computer. When you plug a pen drive into your computer, the virus then jumps to it. If you take it to your friend's house, for example, and then plug it into their computer, the virus will jump to their computer, and so it spreads very quickly. Again, if you are lucky, your computer might stop the virus but on the other hand, it might not.
The importance of keeping virus patterns up-to-date
Anti-virus software is used to help protect your computer against viruses. It does this by checking potential viruses e.g. a file that you have double-clicked on from an email, against patterns of known viruses that it keeps in its database. If it finds a match, it quarantines the virus or deletes it and then tells you. As thousands of new viruses are written every week, it is important to ensure that virus patterns are kept up-to-date. This can usually be done automatically. There are free versions of anti-virus software and there are also many paid-for versions as well. These often come with many additional features and support if there is a problem.