Computer Virus celeberates its 20th Birthday

In January 1986 the first ever computer virus was unleashed via floppy disk, and 20 years on the problem is still very much a nightmare situation for the average PC user.

Though it’s origin is still disputed it is thought the virus, known as Brain, was coded by two Pakistani programmers named Basit and Amjad who designed their virus to affect every 360kb floppy inserted into the drive. Four years later a company called Symantec launched the now hugely popular Norton Antivirus.

Within two years the number of malicious programs had increased by 420% to 1300, this was probably helped by creation kits like the Virus Creation Laboratory which was also released in 1992.

Some of the more memorable viruses since then include 1999’s Melissa virus, which executed a macro which sent copies of itself to 50 people in the users Outlook address book, the Love Bug which deleted MP3, MP2 and JPG files as well as sending usernames and passwords to the author and 2004’s MyDoom worm which affected businesses, banks and the British Coastguard.

Today there are more than 150,000 malicious programs and over 25 major companies specialising in anti-virus software for the Windows platform alone.

Viruses have increased a lot since its birth even with the existance of anti-virus softwares. To fight viruses each and everyone of us should be aware of what they are and how to prevent them. Remember prevention is better than cure. So what is a computer virus?

A computer virus can be defined as an executable program that is capable of infecting other computer programs by modifying them to include a copy of itself.

A computer virus can be thought of as the common cold that spreads when people are in contact with other people.

By infecting computer programs,a virus is capable of spreading through an entire network of computers,like a LAN or WAN. It infects every machine that is incapable of protecting itself. While doing so,it could do a world of damage to you computer, which could cost you a lot. The damage could consist of deleted data,corrupted data,slowing down of infected computer,interruped closing of programs or sudden shutdown of your computer. Sometimes you won’t even realise that your computer is infected by a virus until its too late.

What are the different types of Viruses?

The different types of viruses are:

• File Viruses :

  File viruses are programs that attach themselves to executable files, driver files or compressed files, and are activated when the host program is run. After activation, the virus may spread itself by attaching itself to other programs in the system, and also carry out the malevolent activity it was programmed for. Most file viruses spread by loading themselves in system memory and looking for any other programs code so that it contains and activates the virus the next time its run. It keeps doing this over and over until it spreads across the system, and possibly to other systems that the infected programs may be shared with.

  These viruses can also perform an action based on a particular event or ‘trigger’. The trigger could be a specific date or the number of times the virus has been replicated.

  Example: Randex, Meve, MrKlunky

• Boot Sector Viruses :

  These type of viruses affect the boot sector of a hard disk, which is a very crucial part. The boot sector is where all information about the drive is stored, along with a program that makes it possible for the operting system (OS) to boot up. A boot sector virus can load into memory during every boot sequence, by inserting its code into the boot sector.

  A boot virus does not affect files, instead it affects only the disks that contains them. These viruses used to spread like wildfire during the days when programs used to be carried around in floppies. However, with the CD-ROM revolution, it became impossible to infect pre-written data on a CD, which eventually stopped such viruses from spreading. Hence, these viruses are rare nowadays.

  Example: Polyboot.B, AntiEXE

• Multipartite Viruses :

  Multipartite Viruses are a combination of boot sector viruses and file viruses. These viruses come in through infected media and reside in memory. They then move on to the boot sector of the hard drive. From there, the virus infects executable files on the hard drive and spreads across the system.

  There aren’t too many multipartite viruses in existence today, but in their heyday, they accounted for some major problems due to their capacity to combine different infection techniques.

  Example: Ywinz

• Macro Viruses :

  Macro Viruses infect files that are created using certain applications or programs that contain macros. These include Microsoft Office documents such as a Word documents, Excel spreadsheets, PowerPoint presentations, Access databases, and other similar application files such as Corel Draw, AmiPro, etc.

  Since macro viruses are written in the language of the application, and not in that of the operating system, they are known to be platform-independent, i.e, they can spread between Windows, Mac, and any other system, so long as they are running the required application. With the ever-increasing capabilities of macro languages in application, and the possibility of infections spreading over networks, these viruses are major threats.

  The first macro virus was written for Microsoft Word and was discovered in August 1995.

  Example: Relax, Melissa.A, Bablas

• Network Viruses :

  Network Viruses are proficient in quickly spreading across a Local Area Network (LAN) or even over the Internet. usually, it propagates through shared resources, such as shared drives and folders. Once it infects a new system, it searches for potential targets by searching the networks for other vulnerable systems. Once a new vulnerable system is found, the network virus infects the other system, and thus spreads over the network.

  Example: Nimda, SQLSlammer

• E-mail Viruses :

  An e-mail virus could be a form of a macro virus that spreads itself to all the contacts located in the host’s email address book. If any of the e-mail recipients open the attachment of the infected mail, It spreads to the new host’s address book contacts, and then proceeds to send itself to all those contacts as well. These days, e-mail viruses can infect hosts even if the infected e-mail is previewed in a mail client (such as Microsoft Outlook Express).

  Example : ILOVEYOU virus

How do I know if my pc is infected?

The common symptoms of having a virus or worm on your system are:

• your computer stops responding when you open a certain program
• many dialog boxes appear when you open a strange attachment with double extension
• your anti-virus program is disabled for no reason and can’t be reinstalled
• your friends receive email messages containing infected attachments from you
• unknown icons appear on your desktop that you did not place
• error messages such as ‘Out-of-memory’ appear
• windows restarts unexpectedly
• a partition disappears
• windows restarts when you connect to the Internet
• funny messages appear on your screen
• strange sounds playing from your speaker unexpectedly

The common symptoms of having a spyware or adware on your system are:

• ads popping up even when you are not connected to the internet
• homepage changed to something else such as www.searchallweb.com
• internet connection slower than before
• new search bars in IE browser that you did not install

How do I avoid infection?

• use a good anti-virus software such as Norton AntiVirus and update it regularly
• use a good firewall such as ZoneAlarm
• make sure your antivirus program automatically scans all removal media for viruses as soon as it is inserted
• do not open mails with attachments unless you are sure its safe
• disable the message preview pane in the e-mail client you use
• back up all your important documents and programs on a CD
• update Windows, instant messengers, and every other program you use online