Types of computer viruses

 

There are a lot of types of computer viruses such as Memory Resident Virus , Direct Action Viruses , Overwrite Viruses , Boot Sector Virus , Macro Virus , Directory Virus , Polymorphic Virus , Companion Viruses , FAT Virus , Multipartite Virus , Web Scripting Virus , Worms and Trojans .I will discuss some of them :

1 - Memory Resident Virus :

 

This type of virus fixes itself in the computer memory and gets activated whenever the operation system runs and infects the files that are then opened. These viruses hide in the RAM and stay there even after the malignant code is executed. " They get control over the system memory and allocate memory block through which it runs its own code, and executes the code when any function is executed ". (JayashreePakhare,2012 ).

2- Direct Action Viruses:

The purpose of these viruses is to take action and replicate when they are executed. When a specific condition is met, the viruses will go into action and infect files in the directory or folders that are specified in the AUTOEXEC.BAT file path. These batch files are often located in the hard disk's root directory and carries out certain operations when the computer is booted. Find First or Find Next technique is used where the code selects a few files as its victims. It also infects the external devices like pen drives or hard disks by copying itself on them. The viruses keep changing their location into new files whenever the code is executed, but are generally found in the root directory of hard disk. (JayashreePakhare,2012 ).

                                                                                                                                          

3 -Boot sector viruses :

A boot sector virus infects the boot record on floppy disks , hard disks, and also on CD’s and DVD’s. Boot sector viruses do not need to be able to successfully boot the victims' computers to infect them . As a result , even non-bootable media can spread  boot sector viruses. When the infected computers do successfully boot, the boot sector viruses stay in memory and infect floppies and other media when they are written by the infected computer. A boot sector virus has become less common as floppy disks have become rarer. (tech-faq.com, n.d).

 

4 - Multi-partite viruses :

" Multi-partite virus shares the characteristics of more than one virus type. For example, a multi-partite computer viruses might infect both the boot record and program file " . (tech-faq.com, n.d).

 

5 – Worms:

Worms are  programs that make and facilitate the distribution of copies of themselves; for example, from one disk drive to another, or by copying themselves using email or another transport mechanism. " The worms may do damage and compromise the security of the computers . They may arrive by exploitation of a system vulnerability or by clicking on an infected e-mail ". (topchoicereviews.com, n.d ).

        

                    Interesting Photos about computer virus

 

 

 

 

 

 

 

 

  A computer virus

Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation.

What do computer viruses do?

Through the course of using the Internet and your computer, you may have come in to contact with computer viruses. Many computer viruses are stopped before they can start, but there is still an ever growing concern as to what do computer viruses do and the list of common computer virus symptoms. A computer virus might corrupt or delete data on your computer, use your email program to spread itself to other computers, or even erase everything on your hard disk.

Computer viruses are often spread by attachments in email messages or instant messaging messages. That is why it is essential that you never open email attachments unless you know who it's from and you are expecting it.

Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.

Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.

To help avoid computer viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, run your computer as a standard user (not as administrator), and that you follow a few basic rules when you surf the Internet, download files, and open attachments.

Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection.

from : http://www.microsoft.com/security/pc-security/virus-whatis.aspx 

 

 

 

What can I do to protect myself from computer viruses and Trojans?

 

 

These days, practically everyone's online, downloading and exchanging files, and developers are in such a hurry to get their Web sites up or their files out that checking for a nasty bug is more of a courtesy than a requirement. If you're not careful, your computer can end up with a nasty virus that makes your files act oddly, crashes your computer, pops up bizarre messages, or worst of all, destroys your operating system.

A computer virus is the most subtle of computer problems. It usually loads itself into your computer system when you run a program to which it has attached itself. From the computer system, it'll then reproduce itself, much like a biological virus would, by attaching copies of itself to other programs on your hard drive. What it does then depends on the malevolence of its creator. Some viruses are nothing more than a practical joke. They may bring up a message like "Merry Xmas" or melt your display. Most of them though, either start destroying your system or your files immediately or on a date specified by their creators—like the much-publicized Michelangelo virus, which erases important pieces of your system on March 6. "Trojan horse" programs are similar to viruses in their effect on your system, but they can't reproduce themselves. They're usually a program disguised as something you might want to download onto your computer—for instance, a rogue, modified version of PKWare's PKZIP utility. But when you run the new program you just found, it can do anything from popping up a message to erasing your hard disk, as the rogue PKZIP utility really did.

In either case, you have to actually launch the infected program or the trojan horse for it to infiltrate your system. Though hoax e-mails, like the one about the "Good Times" virus try to make you believe otherwise, neither a virus nor a trojan horse program can do anything if you simply leave the malevolent file sitting on your hard drive.

Finding out that you copied a trojan horse onto your computer is remarkably easy. You launch the program, and the next thing you know, something completely unexpected happens—maybe your system is gone or your computer is laughing maniacally at you. But unless you notice your computer acting oddly before the virus has done its worst damage, you may very well not know you have it until it's too late.

 

From : http://www.allaboutcookies.org/security/