Top 10 things everyone must know about computer viruses

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Author: Eric Koshinsky

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Top 10 things everyone must know about computer viruses

Eric Koshinsky

http://www.antivirus-report.com

1. What is a virus?

A virus is the name for a parasitic program written to intentionally enter a computer without the user's permission or knowledge. The word parasitic is used because a virus attaches to files or boot sectors and replicates itself so it can spread. Though some viruses do little more than copy themselves, others can cause serious damage or affect program and system performance. Therefore a virus should never be assumed harmless or left on a system.

2. One way you can’t get a virus

You cannot get a virus simply by being on the internet or using an online service. You will only become infected via the internet if you download an infected file and then run that file.

3. Three ways you can get a virus

There are only three ways you can get a virus: i) by executing an infected program ii) booting from an infected diskette iii) opening an infected email attachment. Strictly speaking i) and iii) are pretty much the same, but most people think of them quite differently, so I will too.

4. What are infected program viruses?

Infected program viruses are often attached to other software programs like games, disk utilities, the macros in office documents and screen-savers. They are activated when these normally harmless programs are started. When the infected application is run the virus activates and loads into memory, where it can infect any new program that you open. This means that ever more applications on your system will become infected, which will almost certainly cause system problems. Files downloaded directly from the Internet (either through file-sharing programs or direct download from websites), are among the fastest growing sources of computer virus infections.

5. What is a boot infector?

Booting from an infected disk simply means allowing your computer to start up with a disc, CD or DVD in the drive. Even so called ‘non bootable’ diskettes, CD's, and DVD's can be infected by a boot sector virus, so make a point of removing all kinds of discs when you’ve finished with them. Once the ‘boot code’ on your hard drive is infected, the virus will be loaded into your computer’s memory every time you start your computer, from where the virus can infect each and every disk that is put into your computer. Floppy disks, though not as commonly used as in the past, are still a very common way viruses being spread from machine to machine. Anyone with an infected machine, using a floppy disk to copy and save files, can also copy and transfer the virus.

6. How do email infections happen?

Email is now a favorite way to spread viruses. They are contained in the attachments (the files that can be sent along with an e-mail message). Often the user of an infected computer unknowingly attaches an infected file to an email message, and then sends the email to a friend or colleague. When the email is received and the file attachment is opened, the virus launches itself. Email messages with animations, automated greeting cards, jokes, photographs, even spreadsheets and document files, all have been documented to contain virus files. Many of the most dangerous viruses are primarily spread through e-mail attachments.

7. One simple way to avoid infections

Obtain software from reputable sources. Downloading a service pack for Windows NT from Microsoft's web site is a very different proposition than downloading a freeware disk utility from a company you've never heard of, on a site in a province of the former Soviet Union. You use common sense – for instance, beware of Automatic Downloads – take care when using programs that download and run update patches and programs automatically. While in most cases these will not be a problem, having downloaded software run automatically without virus checking exposes you to potential problems in my opinion. Regardless of where you get your software even shrink-wrapped CDs from a reputable supplier, ALWAYS scan it for viruses BEFORE you execute the program or installer.

8. A second simple way to avoid infections

Control your network connections and access to your computer. You could limit access just to those who have a need - fully 80% of damage caused to information systems is caused by action taken (either accidental or deliberate) by an employee or friend, and not from outside sources.

9. Be safe rather than sorry

Make sure you have backups for all your files. Backups are essential not only to safely recover from virus infections, but also to recover from the other threats to your data (such as a hard disk failure or a major coffee spilling accident).

10. Use quality virus protection software

Last, but certainly not least, use good quality market leading commercial virus protection software packages. The primary benefit of using top commercial software is the frequency and ease of updating the virus definition files that these programs use to detect viruses. With new viruses popping up all the time, unless your protection software is kept updated (daily and automatically), you become ever more vulnerable to infection.

Twelve Threats No Computer User Should Ignore

The internet is undoubtedly a fantastic resource for families and offers a rich vein of educational content.

However, there are potential dangers - welcome to the seedy world of viruses, spam, trojans, pornography, spyware and other nasties.

These are the Top Twelve Threats No Computer User Should Ignore.

1. Viruses - A computer program that copies itself. They often disrupt your computer system or damage your data. Viruses are usually received by email attachments so be careful opening anything from a dubious source. They can affect anyone, for example, the destructive Mydoom worm affected one out of three small and mid-sized businesses.

2. Spyware - Sends information about you and your computer to somebody else. Spyware may send the addresses of sites you have visited or worse still, transmit personal information. With today’s concerns about identify theft this is a real worry. For example, CoolWebSearch may hijack web searches, home page, and other Internet Explorer settings. Spyware is normally received as part of shareware or freeware downloaded from the web.

3. IP Spoofing - A technique to gain unauthorized access to computers, whereby the intruder sends messages to a computer with an address indicating that the message is coming from a trusted host.

4. Trojans - An apparently legitimate computer program that is really intended to disrupt and damage computer activity by sending information, perhaps even passwords onto a third party without you knowing. As an example, recent emails entitled "Osama Bin Laden Captured" attempted to download the "Trj/Small.B." Trojan if the embedded URL was clicked. This trojan attempts to hijack the PC.

5. Spam - Unsolicited mail often promoting products of a dubious financial or sexual nature. Don't leave your email address on websites and internet bulletin boards as they are harvested by spammers.

6. Adware - puts advertisements on your screen. These take many forms including popups, popunders and advertisements that appear later, even if your browser is closed. Some are sent using the Windows Messenger service which allows a spammer to direct an advertisement straight to your computer by sequentially sending messages to IP addresses. Always irritating, they are also often of a pornographic nature.

7. Diallers - for those of us still with dial up modems, dialler programs redirect calls to a very expensive number. You won’t know until you get the bill.

8. Hijackers - Hijackers take control of your web browser and may reset your home page, search bar and search pages. They can redirect you to undesirable sites or stop you going to particular sites.

9. Hackers - With so much personal data available online to anyone with a password you must be sure your password is secure. If you are using your mother's maiden name, your cat's name or your birthday then your password is at risk. Here are two tips for making a secure password. Method One - pick two random unrelated three letter words and two digits. Mix them up and what do you have? A secure password such as "red19cat" or "hotpin73". Method Two - pick a short sequence of words such as Now Is The Winter Of Our Discontent Made Glorious' and you have a password of "nitwoodmg". You could even change the I's and O's to digits.

10. Phishing - Emails purporting to come from reliable sources such as Paypal, Ebay or your bank. Often wanting you to verify your account details, they can look very realistic but are generally scams to harvest usernames and passwords. Always open a new browser winder and type the address there, rather than clicking on the link provided.

11. Hoaxes - Chain letters, scams, false alarms. At best they take up time and bandwidth but at worst vulnerable can be victims of fraud. Pass it on!

12. Stranger-danger – For those of us with children - do you know what they actually do when they are online? Are they working on homework tasks, downloading illegal music or pornography? Or are they chatting to strangers in chat rooms? You should consider blocking access to undesirable sites and logging their activity with a surveillance tool. Oh, and don't forget that where children are concerned, computers should always be kept in a family room and never in their bedroom.

Three Step Action Plan

There are three basic, essential steps that should be taken to ensure your PC is kept threat-free.

Firstly, be sensible when opening attachments or following email instructions from apparently reputable sites.

Secondly, make sure you are using the latest service pack of Windows as Microsoft is continually closing loopholes to tighten up security.

Finally, there's a range of low cost tools such as firewalls, antivirus, spam blockers and spyware killers available. Like everything else they vary in quality and you tend to get what you pay for so always do your research first and perhaps try a free trial before getting your credit card out.