COMPUTER VIRUS

What Went Wrong - How Did my System Get Infected with a Virus?

There are a number of warning signs that indicate the presence of a computer virus infection on your computer system.

The same symptoms apply to worm infections and Trojans, malicious code often delivered via contaminated email attachments. The major warning sign is a dramatic decrease in your machine's operating speed, especially if you are connected to a network.

Look for strange operating behavior such as flashing drive or modem lights, corrupted or lost files (especially Word documents and Excel spreadsheets), or unusual program messages (for instance messages that say your files are not in the correct format.) Sometimes programs are disabled and will not open or new icons appear on your desktop. Your speakers my play strange sounds or your monitor's display may be disrupted.

Frequent and unexplained systems crashes are common symptoms of virus infection. Sometimes the system will "han" on start-up or will take an unusually long time to start. You may receive "out of memory" messages or be unable to install new programs. But how does a virus infect your computer in the first place?

How do Computers become Infected by Viruses?

The simple answer to "how do computer viruses infect your computer" is that you have most probably been tricked into doing something that you shouldn't have done, thus allowing the virus to be activated and to propagate. Some of the worst virus and worm infections are attributed to email messages.

The vast bulk of viruses are distributed as attachments to trick email messages. The best piece of advice anyone can follow to protect themselves from computer viruses is, do not open attachments - especially those with the file extensions .vbs or .exe. If you receive a message with an attachment, even from someone you know, send an email asking what the attachment is about and even if they actually sent it.

Many viruses, once activated, send themselves to every email address in the contact list of the infected machine. The virus is designed to appear to be sending benign or useful material or programs. Be suspicious! If you are sending an attachment, clearly state in your message what you are sending (format and content) and expect the same courtesy and caution from your correspondents.

 Some Viruses can Crash you PC. Check out the Types of Viruses

People have a very general view that there are many types of computer viruses and are those programs that cause damage or make the system crash.

Malicious code is the general word used and virus is one type of malicious code. Worms and Trojans are different from computer virus and destructive types of worms are sometimes termed as internet types of virus. Computer viruses have made their mark on the PC's since the 90's with different types of viruses causing damage to computers.

The earliest viruses made the most impact as no anti-virus programs were available. The advent of anti-virus programs spelled a death blow to many common types of computer viruses that were written by the various tools to generate types of computer virus. Those who were inept at programming used these various tool to generate the virus. Devious mind always find new ways when they found that the anti-virus software's were able to disinfect and remove the different types of computer viruses they went on to new methods and that is how Trojans and worms came up.

There are a few main types of computer viruses and these computer virus types are classified below depending upon the infection methods:

Boot sector/Master Boot Record Computer Virus

Means of Infection

Boot sector is that area of the computer that is accessed when the computer is turned on. A boot sector virus infects this portion. Once the boot sector is infected the virus is loaded into memory when the computer is turned on. This virus then infects boot sectors on floppies or other removable media Master Boot record virus only infects the Master boot record and not the boot sector

Damage Caused

Boot sector viruses gain complete control of the master boot record or the DOS boot sector by replacing the operating system contents with that of its own. This allows the virus to spread fast and cause damage:

• By gaining control of the master boot record and the DOS boot sector the boot sector viruses can sometimes hide the resources that the computer has( the floppy drive even though attached may not be present)
• Some boot sector viruses contain instructions to redirect disk reads.
• Some boot sector viruses move the master boot record to another location causing the system to crash when it boots up. Other boot sector viruses cause damage to the master boot record
• Some boot sector viruses damage the File Allocation Table (FAT) which is the index of all the files on the drive. This causes loss of data

Removal

The best way to remove boot sector virus is to boot the computer with using a clean boot disk and then rewrite the files with the good operating system files on the infected disk. These viruses were very much prevalent in the ninety's and a host of antivirus programs are now available to detect and clean them effectively. Spyware remover helps to keep off the malicious spyware to protect your PC and enhances good performance and speed up your PC.

Continue to : Different Types of Viruses

Boot Sector VirusBrowser HijackerDirect Action VirusFile Infector VirusMacro VirusMultipartite VirusPolymorphic VirusResident VirusWeb Scripting VirusTrojan horse