Virus is a harmful computer program that enters the computer system, attaching itself to another program and causes damages to system and programs.
How does a computer get affected by virus?
- By sharig files with other users.
- Visiting an infected web site.
- Opening e-mails from anonymous senders.
- Downloading games, free music, videos or programs from unknown sites.
Harmful Effects of Computer Virus.
- Virus can corrupt your programs (programs start malfunctioning or stop working)
- It can delete files in your computer.
- It can format your Hard disks.
- Some viruses simply replicates and fills the hard disk with useless data.
- They can reduce computer memory and cause frequent computer crash.
Symptoms of a Computer Virus.
- Slowing down the performace of computer.
- Unexplained data loss.
- Unusual display on the screen.
- Sudden decrease of space in your Hard disk.
TYPES OF COMPUTER VIRUSES
1. MACRO VIRUS
These are viruses affecting documents such as Word ad Excel files. These viruses get transported along with these files.
e.g: Melissa, Bablas.
2. FILE INFECTOR
These viruses may completely overwrite your files, causing data loss.
3. RESIDENT VIRUS
This is a virus that enters the system memory.
4. NETWORK VIRUS
These viruses spread across local area network and internet.
e.g: Nimda, SQL Slammer.
5. BOOT-SECTOR VIRUS
This virus hides in the boot sector of the hard disk. And it gets loaded in to the computer every time your computer starts.
6. MULTIPARTITE VIRUS
This virus spreads through infected CDs ad pendrives.
7. TROJAN HORSE
Trojan virus disguises itself as a game or utility program, but when executed it destroys the data stored in the computer..
ADWARE, MALWARE & SPYWARE
It is a software which displays uwanted advertisements.
A software which steals information from your computer without your kowledge.
MALWARE (Malicious Software):
All the harmful programs like worms, Trojas, Spyware, adware, scareware, or crimeware which are desiged to damage the computer are collectively called as Malware.
It is a small software that replicates itself and spread through network.
PROTECTING A COMPUTER FROM VIRUSES
Install a good Antivirus program.
Use antimalware programs.
Update your Operating System regularly.
Update the Antivirus program regularly.
Visit only trusted web sites.
Always scan CDs and pen drives before using them.
Do not use pirated software.
Turn firewall on in your computer.
Do not open attachments from anonymous emails.
How Does an Antivirus Work?
- Antivirus program runs in the background (on-access scanning)
- It checks every file you open and if the file is infected it delete the file or tries to repair it.
Examples for some popular Anti-virus program are:
- Quick Heal.
- Norton’s Antivirus.
- McAfee Security