What is Computer Virus ?

A computer virus is a set of malicious code or program written to alter the way a computer operates. It is usually designed to spread from computer to computer. A virus operates by inserting or attaching itself to a legitimate program or document support macros in order to execute the codes.

A virus has the potential to cause unexpected or damaging effects such as harming system software by corrupting or damaging data. Once a virus successfully attaches itself to a program, file or document, the virus will remain dormant until circumstances cause a computer to execute its code. In order for a virus to infect any computer, the infected program has to be run in order for the code to be executed.

Signs of Computer Virus

  1. Frequent pop-up windows
  2. Changes your homepage
  3. Mass email being sent from your email account
  4. Frequent crashes
  5. Slow computer performance

Different types of Virus

1. Boot sector virus

This type of virus can take control when you start or boot your computer. It spreads by plugging Flash drives.

2. Web scripting virus

This type of virus exploits the code of web browsers and webpages. It spreads through infected webpages.

3. Browser hijacker

This type of virus hijacks certain web browser functions and might automatically be directed to unintended sites.

4. Resident virus

This is the general type of virus that inserts itself in a computer system memory. A resident virus can execute at any time when the operating system loads.

5. Direct-action virus

This type of function comes into action when you execute a file containing a virus otherwise it remains dormant.

6. Polymorphic virus

A polymorphic virus changes its code each time the infected file is executed. It does this to invade antivirus.

7. File infector virus

This common virus inserts malicious code into executable files. i.e. files used to perform certain functions or operations on a system.

8. Macros virus

Macros virus are written in some macro language used for a software application. Such virus spread when you open an infected document often through an email attachment.

Prevention of Virus

  • Password protection should be employed. 
  • Execute familiar programs only as to their origin. Programs sent by e mail should always be suspicious. 
  • Load software only from original CDs or disks instead of pirated or  copied ones. 
  • Check all shareware and free programs downloaded from online  services with a virus checking program. 
  • Computer uploads and “system configuration” changes should be  always performed by the computer owner. 
  • Purchase or download an anti-virus program that runs as you boot or  work on your computer. Also, update it frequently.

What is Antivirus?

Antivirus is a type of program designed and developed to protect a computer from malware like computer virus, worm, spyware, botnets, boot-kits, keylogger, etc.

Antivirus function to scan, detect and remove such viruses from the computer. Most antivirus incorporates both automated and manual filtering abilities. Instant scanning option may check files downloaded from the internet, disks that are embedded into PCs and files that are made by software installers.

Features of Antivirus

1. Default deny protection

It is implemented to prevent the entry of suspicious files by default.

2. Auto sand-box technology

A virtual environment where suspicious and unknown files are secluded and run to check for any malicious activity without interfering the normal operations.

3. Containment technology

It validates and authorizes the programs that are executable and ensure that processes are running without affecting the regular operation of the system.

4. Host intrusion protection system (HIPS)

It terminates any malicious activity once found. This prevents malware from infecting the operating system, registry keys, personal data or the system memory.