Also read: Choose a good Antivirus, which best suites your PC
What is a Computer Virus?
- A VIRUS is a small piece of software that piggybacks on real programs, O.S or emails.
- A computer virus is a small program written to alter the way a computer operates, without the permission or knowledge of the user.
- With an ability to replicate itself, thus continuing to spread. Also, known as Malicious Software, a program that can cause damage to a computer.
- The computer viruses can damage or corrupt data, modify existing data, or degrade the performance of the system by utilizing resources such as memory or disk space.
Classification of Computer viruses:
- Boot sector virus: generally hide in the boot sector
- Master Boot Record (MBR) virus: viruses that infect disks in the same manner as boot sector viruses.
- File infector virus: infect executable code, such as.COM, .SYS, .BAT and .EXE files.
- Multipartite virus: viruses infect both boot records and program files.
- Macro virus: mini-programs which make it possible to automate a series of dirty operations.
These are :
Worms are programs that replicate themselves from system to system without the use of a host file. The worms are spread through networks like LAN, WAN and also through the Internet.
Trojan horses are impostors: files that claim to be something desirable but, in fact, are malicious. Trojan horse programs do not replicate themselves. Trojan horses contain malicious code that when triggered cause loss, or even theft, of data.
Also read: Crazy things you need to know about viruses [Infographic]
- An antivirus software is a computer program that identify and remove computer viruses, and other malicious software like Worms and Trojans from an infected computer. Not only this, an antivirus software also protects the computer from further virus attacks.
- We should regularly run an antivirus program to scan and remove any possible virus attacks from a computer.
How an Antivirus works
- The antivirus software examines each and every file in a computer and examines its content with the virus definitions stored in its virus dictionary.
- A virus dictionary is an inbuilt file belonging to an antivirus software that contains code identified as a virus by the antivirus authors.
- Antivirus software will constantly monitors the activity of all the programs.
- If any program tries to write data on an executable file, the antivirus software will flag the program having a suspicious behavior, means the suspected program will be marked as a virus.
- The advantage of this approach is that it can safeguard the computer against unknown viruses also.
- The disadvantage is that it may create several false alerts too.
How to choose a good Antivirus
When selecting an Antivirus Software to go through the following details
Read the vendors manual for the software. This will help you to understand the advanced options and how to use them according to your preference.
Some of the symptoms of an infected computer:
- Folder Options disappears from the Tools. Now, hidden files cannot be viewed.
Regedit doesn’t work when you try to invoke it from the RUN box.
- Task Manager has been disabled by Administrator.
- In My Computer, Autoplay option appears instead of Open in every drive you enter i.e. when you click on your drive letters (C, D, E, etc) a window opens to select any one program to Open with.
- The computer becomes slow and there is a noticeable delay in characters to appear on the screen when you press in the keyboard.
- Command prompt does open if it does close suddenly.
- You cannot open system utilities like Task Manager, Regedit, Msconfig, gpedit.msc; it opens and suddenly closes.
- It creates new entries & adds values to the existing Registry.
General precautions you should take
- When inserting removable media (floppy, CD, flash drive etc.) scan the whole device with the antivirus software before opening it.
- If you have internet access, make sure you use internet security software.
- Get Windows updates.
- From time to time, update your installed software to their latest version. E.g. (MS Office, Adobe Reader, java, Flash player etc.)
- Last but not least, you should have an updated antivirus guarding your PC all time.