computer virus

COMPUTER VIRUS

A computer virus is a malicious program (malware), written by computer programmers that attaches itself to a computer software or system that infects and destroys other programs and hardware; it is self-replicating and requires a host or executable disk segment.

CLASSES OF COMPUTER VIRUS

There are various classes of computer viruses, Sometimes; virus can be classified by their method of concealment. Notable ones under this group are:

• Stealth Virus: These viruses have a way of hiding themselves to avoid been scanned

• Polymorphic viruses: These viruses have a way of changing themselves to avoid been scanned

TYPES OF COMPUTER VIRUS

• Command File Virus: This class of viruses infects files with “COM” file name extension. A “com” file is an object or binary file containing an executable program that is a replica of the bit patterns that are to be created when he file is loaded in memory. Examples are

Cccp.510: This virus stimulates a hardware failure

A & A.560: This virus plays tricks with the screen of the computer

• Executable File Virus: Executable file virus attaches itself to executable files or program files. These classes of virus infect files with “EXE” file name extension. An EXE file is a program that can be run. Examples are;

AELAX.658:-This virus deletes files

CHEEBA: This virus evades or attack antivirus programs.

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• Boot sector virus: The boot sector is the section of the system software containing the instructions for booting the computer. The boot sector virus infects the boot sector of the disk by replacing the boot instruction with its own program. Example is BRAIN (Pakistani or Lahore). It labels a good sector a bad one, therefore making it inaccessible to DOS i.e. rendering the system unbootable.

• Partition sector virus: These are viruses that affect the partition sector of hard disk and floppies in drive A. A partition sector is the first sector on a hard disk. The partition sector is also called the master boot Record (MBR).An example of this virus is CHANG.MP.3584. This virus overwrites infected files and making sure that the report size of a disk does not match up with its capacity.

• System file virus: These are files that affect system files like config.sys, Hims.sys etc…

EXAMPLES OF VIRUSES

1. Stoned viruses

2. Trojan horse

3. Sleeper

4. Logic Bomb

5. Alabama Virus

6. Christmas virus

7. Disk virus

8. Recycler virus

SOURCES OF COMPUTER VIRUS

The ways or means in which computer viruses get in to our computer system is known as source of computer virus. They Include;

• Infected diskettes

• Infected flash drives

• Infected CD-ROMs

• E-mails

• Internet downloads

• Illegal / cracked software

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VIRUS WARNING SIGNS OR SYMPTOMS OF VIRUSES

There are some signs shown by a system that has been affected by computer virus. They include.

1. Slowing down of response time of the computer

2. Presence of tiny dots on the screen

3. Incomplete Saving of files

4. Corruption of the system set-up instruction

5. Appearance of strange characters on the screen

6. Computer not responding as expected.

VIRUS DETECTION

We have programs for discovering the presence of viruses in the computer ; they are refered to as Antivirus. They signal on the screen “A VIRUS FOUND ALERT”. They detect and protect your computer from viruses. Examples are, Avast, AVG, Norton Anti Virus, McAfee, PC-Cillin98 etc…

There is probably a cure for every computer virus, getting rid of viruses can take a great deal of time. Also, having removed virus does not guarantee that our files will be intact. The best preventive measure from viruses the use of antivirus.

PREVENTION OF COMPUTER VIRUS INFECTION

1. Always buy original software and avoid the use of pirated software

2. Always scan your computer for viruses before the day’s operation

3. Always scan removable disk

4. Always make sure your antivirus is up to date to fight against newer viruses

5. Avoid downloading of unsecure programs online

EFFECTS OF VIRUSES

• Erases bank records

• Corrupts stored files and programs

• Interferes negatively with computer operation

• Damages the computer

Assignment

1. List 5 Computer Virus and explain how they operate.