Virus

[VIRUS: -       Vital Information Resources Under Siege]

A Computer Virus is a malicious software program “Malware” that can infect a computer by modifying or deleting data files, boot sector of a hard disk drive or causes a software program to work in an unexpected manner”.

A computer virus resides on a host computer and can replicate itself when executed. Virus can steal user data, delete or modify files & documents, records keystrokes & web sessions of a user. It can also steal or damage hard disk space, it can slowdown CPU processing.

Definition of Computer Virus

“A computer virus is a program that may disturb the normal working of a computer system”. Virus attaches itself to files stored on floppy disks, USBs, email attachments and hard disks. A file containing a virus is called infected file. If this file is copied to a computer, virus is also copied to the computer.

Activation of Virus

When the computer virus starts working, it is called the activation of virus. A virus normally runs all the time in the computer. Different viruses are activated in different ways. Many viruses are activated on a certain data.

How a computer virus spreads? / Causes of Computer Virus

For a computer virus to spread through a computer system, or network, it must be activated. This means that the file that contains the virus must be opened, or executed in order for the virus to come to life. After it gets activated, these viruses look for certain programs to infect. The main and the important that you must note is that all viruses seem to do well is duplicate themselves within the programs they find, and this is the main reason as to how they spread well.

     a.    Infected Flash Drives or Disks

Flash drives and disks are the main cause of spreading viruses. Flash drives and disks are used to transfer data from one computer to other. A virus can also be copied from one computer to other when the user copies infected files using flash drives and disks.

     b.    Email Attachments

Most of the viruses spread through emails. Email attachment is a file that is sent along with an email. An email may contain an infected file attachment. Virus can spread if the user opens and downloads an email attachment. It may harm the computer when it is activated. It may destroy files on the hard disk or may send the virus automatically to all email addresses saved in the address book.

     c.     Infected websites

Thousands of insecure websites can infect computer with viruses. Most of the websites with pornographic materials are infected, so by visiting these websites the user’s computer also gets infected by virus. These websites are developed to spread viruses or other unethical material. The virus is transferred to the user’s computer when this material is downloaded. These websites may access the computer automatically when the users visit them.

     d.    Networks

Virus can spread if an infected computer is connected to a network. The internet is an example of such network. When a user downloads a file infected with virus from the internet, the virus is copied to the computer. It may infect the files stored on the computer.

     e.    Pirated Software

An illegal copy of software is called pirated software. Virus can spread if user installs pirated software that contains a virus. A variety of pirated software is available in CDs and from the internet. Some companies intentionally add virus in the software. The virus is automatically activated if the user uses the software without purchasing license.

Types of computer viruses

Trojan Horse

A program written to deliver a malicious program that may then cause destruction to your computer. A Trojan horse is delivered by someone or hidden within another program that may seem harmless.

Spyware

A program written to monitor your actions on a computer. A common type of spyware is a key-logger program. This program can record every key stroke and mouse click you make. Spyware can be delivered via a Trojan horse program.

Adware

Adware is a form of malware. One word - pop-ups. Adware is designed to pop up advertisements. Adware can be very annoying.

Worms

Just a nasty little program to cause slowness in a network. A worm will replicate itself and spread from computer to computer. Worms are commonly spread through email attachments.

Boot Sector Virus

Not so common anymore, but they were nasty little programs that got loaded into your master boot record. Most commonly spread by floppy disks. These viruses could then launch themselves before your operating system even loaded.

Time Bomb

A virus written to execute at a later date or upon an action performed. These programs lay dormant until an event occurs.

Browser Hijacker

A virus that will over take your web browser and automatically redirect you to another website.

File lnfector Virus

A virus that lives within a file, typically a .exe file. When the file is executed, it will then run its nasty code.

Polymorphic Virus

A virus written to change itself in order to evade virus detection.

Macro Virus

A virus that hides itself inside of macros used by programs such as Microsoft Excel.

Web Scripting Virus

A virus that hides within a website. Some are put there on purpose, some get injected into websites that are not properly secured.

Damages caused by virus

Computer virus cannot damage computer hardware. It may cause many damages to a computer system. A virus can:

1.                 A computer virus can damage data or software on the computer.

2.                 It can delete some or all files on the computer system.

3.                 It can destroy all the data by formatting hard drive.

4.                 It may display a political or false message very few times.

How to detect a virus (signs of virus being infected)

Signs of an infected computer can be numerous depending on which virus your computer is infected with.

1. Computer speaks to me.

There are all types of pop-ups and messages on the desktop either advertising things, saying that the PC is infected and needs protection.

2. Computer is running extremely slowly.

This could be a symptom of many things, including infection by a virus. If it has been infected by a virus, worm or Trojan, among other things, which are running on the computer, they could be running tasks that consume a lot of resources.

3. Applications won't start.

Sometimes another program might even run. As in the previous case this could be another type of problem, but at the very least it's a symptom that tells you that something is wrong.

4. Unable to connect to the Internet or it runs very slowly.

Loss of Internet communication is another common symptom of infection, although it could also be due to a problem with your service provider or router.

5. When connect to the Internet, all types of windows open or the browser displays pages I have not requested.

This is another certain sign of infection. Many threats are designed to redirect traffic to certain websites will, and can even spoof Web pages against the user's .

6. My antivirus has disappeared, my firewall is disabled.

Another typical characteristic of many threats is that they disable security systems installed on computers. Perhaps if one thing shuts down it might just be a specific software failure; but if all, your security components are disabled.

7. Library files for running games, programs, etc. Have disappeared from my computer.

Once again, this could be a sign of infection, although it could also be down to incomplete or incorrect installation of programs.

To check for viruses, scan your computer with an antivirus program. New viruses appear every day, so keeping your antivirus program updated is important.

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