Ashok Negi asked:


Computer Viruses:-

 

The world of computers and information technology is going through an era of an electronic terrorism, in the form of the computer virus. It is a problem that is potentially so dangerous that it threatens the proper functioning of the virus system in today’s information age.

The virus whether biological or electronic is an information disorder. Biological viruses are tiny genetic codes DNA or RNA that take over the machinery of a living cell and are capable of marking thousand of replicas of the original virus. Like its biological counterpart, a computer virus carries in it an instructional code that makes copies of itself.

Computer viruses are computer programs which are a collection of coded instructions. The basic difference between a normal program and virus is that viruses are self replicating; they have the capacity of executing themselves without being asked for. The ‘Computer virus’ is a very broad term in itself and includes not only viruses, but also worms and Trojans.

 

Classification of Computer viruses:-

 

Viruses are classified on the basic of their mode of existence and there are three categories of viruses.

 

1. BOOT  Infector:-

2. SYSTEM  Infector:

3. GENERAL EXECUTABLE PROGRAM   Infectors:-

 

BOOT Infectors:-

As the name suggests, they are characterized by the fact that they are physically reside in the boot sector [0] sector of the disk. A system infected by such a virus will have the virus residing in a particular area of the disk rather then in a program file. These viruses get loaded soon after the Power Of Self Test and control the system and remains in control at all times. They some times have the capacity to trap soft booting (CTRL ALT DEL) and remain in control even if the system is booted from a non infected floppy, thereby contaminating the clean floppy.

 

SYSTEM Infectors:-

The second category of virus deals with components of the system itself. All machines without execution require an operating system in order to create an environment in which the operator works. In MS-DOS, COMMAND.COM contains all the internal commands. If no such command file exists, commands such as COPY, DIR etc. are not loaded into the memory when the machine is booted. The system infectors attach themselves to a file such as COMMAND.COM or other memory resident files and manipulate these files.

 

GENERAL EXECUTABLE PROGRAM Infectors:-

From the infection point of view, these are most dangerous and devastating of the three classes of viruses. They attach themselves to program files and can spread to almost any executable program in any system. These viruses change the original program instructions into a “jump” to its own code and follow that code with a return to the original program. As a result, whenever the program is executed, the virus gets loaded and executed first and then allows the original program to process. It remains memory resident and infects each and every program that is loaded for execution.

 

Types of Viruses:-

 

Worms:-

A worm is software that uses computer networks and security holes to replicate, or affect other programs. A copy of the worm passes through the network to another machine that has a specific security hole. It then copies itself to the new machine, and then starts replicating from there.

 

Macros:-

Macro viruses’ use commands-called macros-embedded in the other software applications to infect and spread to other files used by that software. For example, Microsoft Word and Excel have macros, and macro viruses can spread by exploiting these commands.

 

Boot Sector viruses:-

Boot sector viruses are older types of virus and are not so common today. They used to infect computers startup programs, so that the virus would become active as soon as the computer started up.

 

Trojan Horses:-

Trojan Horses are programs that claim to perform a particular function but which in fact do something different. For example, they could infect your computer with a virus or erase your files.

 

Backdoor Trojans:-

Backdoor Trojans are programs that allow other computer users to remotely control your computer via a local area network or the internet.

 

Resident Viruses:-

These types of virus hides permanently in the RAM memory. From here it can control and intercept all of the operations carried out by the system corrupting files and programs that are opened, closed, copied etc.

 

Direct Action Viruses:-

When a specific condition is met (such as the execution of the virus) these virus will go into action and infect files in the directory or folder that it in and others as well.

 

Overwrite Viruses:-

These types of viruses are characterized by the fact that it deletes the information contained in the files that it infects, rendering them particularly or totally useless once they have been infected.

Pc Repair Experts asked:


If you’ve purchased a computer, or are just learning about using email and the internet, you may be faced with the problem of abnormal function of PC or system hanging problem very soon.

Somewhere down the line, there will be problems with your computer (adware, spyware, viruses, good software gone bad, etc,). Obviously, you should use protection software to prevent as much as possible. Internet is one the major source of computer virus. Usually they enter your program through an email, or while you are browsing a website.

When these programs run, usually without you knowing, they can cause all types of problems with your computer. Some viruses can be mildly annoying, slowing down your computer as they use your computer’s resources for another purpose. Others can be very dangerous, collecting your personal information and sending it to another party, or damaging your hard-drive.

Once you realize that you need anti-virus software installed and running on your computer, you’ll have to choose which one to purchase and install. This can be a complicated process, but here are some tips to make it a bit easier.

First, check your computer to see if it came with anti-virus software. Many new computers are shipped with anti-virus programs already to go on them, you just need to turn them on. Check your instruction manual to see if this is the case with your computer.

Check with the vendor. If you purchased your computer from a local retailer, check with them to see what anti-virus program they recommend.

I think that the best way to cure virus/worm problems is to prevent them from happening, and the best way to prevent them from hapenning is through education and awareness. Being a geek, understanding viruses seems to come naturally to me, so I figured I would share information about them with others.

If you are new to computers, please take some time and seek out professional assistance — the rest of the Internet will thank you for it.

Here’s some general tips for staying safe online:

Download and install the Firefox web browser and use it exclusively instead of Internet Explorer. IE is chock full of security holes, and new ones are being found all the time. Using IE is a big liability these days.

tommy amunto asked:


Nowadays, the term of Computer Virus sound familiar for us. Every day we heard millions computer infected by a Computer virus, or a virus make Internet connection trouble, and many more. A computer virus is a computer program that can copy itself and infect a computer without authorization or knowledge of the computer user. Virus can destroy your data, damaging programs, steal important information, or reformatting the hard disk to make your computer completely useless.

If you ask how virus infects a computer, there’s a many way to make it possible. A Floppy Disk, a CD, USB Flash Disk, Zip Drive or even Internet. Today, a virus able to infect a computer from Internet, or network services such World Wide Web, e-mail, Instant Messaging and file sharing systems. Some virus even no needs human action to spread itself. They able to use Operating System bug to infect a computer.

So, now you know what is a computer virus and want to prevent your computer from virus. Or maybe, your computer already infected by virus. Don’t worry. I will help you for solve this problem.

First, install an anti virus program. If a computer virus is programmed to damage the computer, then an anti virus is programmed to prevent, destroy and heal your computer from virus. There’s a many anti virus today. You can use Norton Antivirus, Kaspersky Antivirus, Panda Antivirus or AVG Antivirus. If you don’t have an anti virus, then get one for you. Buy it from computer software store or download from Internet. And make sure to buy or download the latest release. And the most important things are make your anti virus definition up-to-date. Most of anti virus have an automatic update system. You only need to connect your computer to Internet and let them do it automatically. An up-to-date anti virus makes the anti virus know the latest virus and how to remove them.

If you connected to Internet, you need to install a firewall program. A firewall is a computer program designed and programmed to watch an Internet connection on your computer. And if there is an unusual action, they prevent the action. Or in other word, a firewall is a “police” to watch Internet and prevent “bad thing” do some action on your computer. You can use software-based firewall like Norton Internet Security, Zone Alarm and Trend Micro.

Always update your Operating System. There is no perfect Operating System, nor Windows, Linux or Macintosh. There are many bug on them. Usually, an Operating System vendor release a bug fix to patch the bug. So, you need to update your Operating System. Up-to-date Operating System also make your computer immune from another threats.

Gaurav Walia asked:


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Does your computer seem to be running slower than usual? If you’ve using the Internet over the past month, your computer may be infected with a computer Virus that your current Anti-virus software may have failed to detect and remove.

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Disables any computer Worms and Hacking tools from entering your computer

Your PC might appear clean… but it could still be full of ‘Virus threats’ that most antivirus programs fail to detect and it might very well be a Serious threat to your privacy as many viruses now record everything you type on your PC and broadcast it to the internet. This may include credit card numbers, passwords and sensitive information. Most Anti-virus programs fail to detect all viruses and users need an independent virus scanner in order to detect all viruses in your PC.

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Daniel Davis asked:


Computers have incredible capabilities. They can accomplish great tasks, communicate clearly, make things move and think beyond human measure. Computers have become like humans in nearly every conceivable manner, so it’s no surprise that computers can also get sick.

The computer revolution first began picking up speed in the late 1980s. Since then, it has evolved to be a vital element in our society, our corporate and our personal lives. Computers have become part and parcel to virtually everything we do day in, and day out. But with all good comes a little bad. Some users have maliciously created computer viruses that have grave effects. The range of computer viruses existing in our modern networks has a huge prominence in our lives, because of all the ways we depend on computers. Despite our need for dependable computers, some people have nothing better to do but exercise their computer knowledge in a destructive way, creating computer viruses.

The first computer virus, called “The Brain”, was created in 1986. The Brain is a boot-sector virus, which occupies unused space on the disk to eliminate further use of memory space. After it was created, The Brain quickly spread worldwide in 1987. The Brain virus was considered first to use stealth techniques, making the virus difficult to detect.

On November 1, 1987 another virus appeared. The Lehigh virus was named after Lehigh University, the place where this particular virus was first discovered. One Friday the thirteenth, in December of that same year, the Jerusalem virus was discovered at Hebrew University. This virus has also gone by the names “ArabStar”, “Friday the 13th” and the “Black Window”. This is one of the oldest and best-known computer viruses in the world.

Two more viruses surfaced in 1988: the Stone, which was the first bootstrap virus, and the Internet Worm. The Internet Worm caused mayhem in the corporate world as it crossed the United States overnight through a series of computer networks. Then in 1989, the Dark Avenger was introduced. This was a fast-infector that possessed the capability to infect new files despite the presence of anti-virus software. The Dark Avenger computer virus was designed to damage a system slowly. The virus would go unnoticed at first, and damaged files would not be backed up. Slowly it would consume more and more of your computer until it had created permanent damage.

Computer manufacturers and software engineers began the public war against computer viruses around 1990. Corporations began to respond to growing public concern and the number of anti-virus products began to rise. The threat of computer viruses was finally taken seriously. McAfee, IBM, Digital Dispatch and Iris all introduced their anti-virus products and software in 1990. Despite their efforts, computer viruses grew faster, stronger and sneakier. Symantec Norton anti-virus was introduced was introduced in 1991.

The introduction of Windows 95 brought both relief and discomfort to anti-virus companies when it was released in 1995. At that time, most common computer viruses were still boot viruses that worked on DOS, but couldn’t replicate on Windows 95. Then micro viruses were discovered in late 1995. These computer viruses performed in the MS-Word environment, rather than DOS. Again, the anti-virus industry faced challenges to fight against these new batches of viruses. With the introduction and growing popularity of the Internet in the late 1990s, viruses began to spread at a much faster rate.

Throughout 1998 there was no lessening of computer virus attacks MS Office, MS Windows, MS Office and network applications. New viruses continued to appear, and computers and advanced network-to-do applications continued to be affected. In 1999, another virus appeared, infecting computers using Microsoft Word. This computer virus may have been passed on via MS Outlook, or through Outlook Express e-mail programs.

The “Loveletter” virus, also known as “Love Bug” and the “I Love You” virus, is believed to have struck one in five PCs worldwide, making it the most widespread and the most costly computer virus the world had ever seen. The “I Love You Virus” created panic and discord around the globe. The virus was transferred by e-mail. When the receiver opened the attachment, the virus was automatically sent to everyone in the user’s address book. The “I Love You” computer virus spread at a dizzying rate of speed.

As long as we continue to use the Internet and share computer files, we are at risk of catching computer viruses. Even today, more and more viruses are still being discovered, leading to big problems for all users, and creating ongoing dilemmas for the creators of anti-virus programs.

Like people, getting sick is an unfortunate fact of life for computers. Using up-to-date anti-virus software is a sort of preventative medicine, helping to keep computers healthy and computer viruses at bay.