What is a computer virus?
How does a computer virus find me?
What does a computer virus do?
What are the symptoms of a computer virus?
Computer Virus Help: Arming yourself with the best computer virus protection?
How work Computer Virus
our operating system made of two main files
one is com file and other is exe or sys file
Since a virus’ goal is to get executed by the computer, it
must attach itself to a COM, EXE or SYS file. If it attaches to any
other file, it may corrupt some data, but it won’t normally get
executed, and it won’t reproduce. Since each of these types of
executable files has a different structure, a virus must be designed
to attach itself to a particular type of file. A virus designed to attack
COM files cannot attack EXE files, and vice versa, and neither can
attack SYS files. Of course, one could design a virus that would
attack two or even three kinds of files, but it would require a separate
reproduction method for each file type.
The next major type of virus seeks to attach itself to a
specific file, rather than attacking any file of a given type. Thus, we
might call it an application-specific virus. These viruses make use
of a detailed knowledge of the files they attack to hide better than
would be possible if they were able to infiltrate just any file. For
example, they might hide in a data area inside the program rather
than lengthening the file. However, in order to do that, the virus
must know where the data area is located in the program, and that
differs from program to program.
This second type of virus usually concentrates on the files
associated to DOS, like COMMAND.COM, since they are on
virtually every PC in existence. Regardless of which file such a
virus attacks, though, it must be very, very common, or the virus
will never be able to find another copy of that file to reproduce in,
and so it will not go anywhere. Only with a file like COMMAND.
COM would it be possible to begin leaping from machine
to machine and travel around the world.
Types of Computers Viruses
- File virus : Most viruses fall into this category. A virus attaches itself to a file, usually a program file.
- Boot sector virus : These viruses infect floppy and hard drives. The virus program will load first, before the operating system.
The final type of virus is known as a “boot sector virus.”
This virus is a further refinement of the application-specific virus,
which attacks a specific location on a computer’s disk drive, known
as the boot sector. The boot sector is the first thing a computer loads
into memory from disk and executes when it is turned on. By
attacking this area of the disk, the virus can gain control of the
computer immediately, every time it is turned on, before any other
program can execute. In this way, the virus can execute before any
other program or person can detect its existence.
- Macro Virus : This is a new type of virus that use an application's own macro programming feature to distribute themselves. Unlike other viruses, macro viruses do not infect programs; they infect documents.
- Virus Hoax : Although there are thousands of viruses discovered each year, there are still some that only exist in the imaginations of the public and the press - known as virus hoaxes. These viruses hoaxes DO NOT EXIST, despite rumor of their creation and distribution.
How to avoid email viruses and worms
- Use a professional and dedicated email service such as Runbox with strong virus filtering. Subscription services often provide higher levels of security and support.
- Make sure that your Runbox virus filter is activated.
- Use the Webmail interface at www.runbox.com to read your email, as it will never open an attachment by itself.
- Don’t download all your email to an email client unseen. Screen your email first, and delete suspicious-looking and unwanted messages before downloading the legitimate email to your local email client.
- Make sure your computer has updated anti-virus software running on it. Automatic updates are essential for effective virus protection. Combined with server side scanning, you now have two layers of security.
- Disable message preview in your email client, especially on Windows platforms. Otherwise, malicious programs attached to incoming messages may execute automatically and infect your computer.
- Ignore or delete messages with attachments appearing to be sent from official Runbox email addresses. We practically never send email with attachments to our customers, so if you receive such an email it could be falsified.
- Take caution when opening graphics and media attachments, as viruses can be disguised as such files.
- Maintain several independent email accounts. If a virus infects your only business email address, you’ll be in trouble. Also, keep backups of your most important email and files separately.
- Do not open an email attachment unless you were expecting it and know whom it’s from.
- Do not open any unsolicited executable files, documents, spreadsheets, etc.
- Avoid downloading executables or documents from the internet, as these are often used to spread viruses.
- Never open files with a double file extension, e.g.
filename.txt.vbs. This is a typical sign of a virus program.
- Do not send or forward any files that you haven’t virus-checked first.
How to Remove a Computer Virus
We all know malware is out there.Malware includes applications that spy on you, corrupt your data, destroy your hard drive or give control of your machine to someone thousands of miles away. No matter what form it takes, it's bad business. And since there are a lot of examples of malware in the wild, it may only be a matter of time before you become the victim of a malware attack.
The most important advice we can give anyone who believes he or she has a computer with malware on it is this: Don't panic. Also, don't assume that you need to wipe your computer clean and start from scratch. Often you can remove malware without having to erase everything else. You may lose some data in the process, but you probably won't lose everything.
First you need to determine if your computer has a virus at all. You might suspect your computer of having a virus if it seems to be sluggish. If your Web browser suddenly looks different or automatically goes to a site you don't recognize, that's a good indication that you've got some malware. If your computer is unstable and crashes fairly often, you may have a problem. And if you try to access files but receive a message saying they're corrupted, that's another sign.
If you do think your computer has a virus, you need to run antivirus software to weed it out. Some viruses disable antivirus software -- they're clever that way. If you don't have any antivirus software, now's a good time to purchase or download an application. A few malware variants will try to block you from downloading antivirus software. If that's the case, you may need to download the software on another computer and transfer it to disk or a flash drive.
Detecting and Removing a Computer Virus
Antivirus software is practically a requirement for anyone using the Windows operating system. While it's true you can avoid computer viruses if you practice safe habits, the truth is that the people who write computer viruses are always looking for new ways to infect machines. There are several different antivirus programs on the market -- some are free and some you have to purchase. Keep in mind that free versions often lack some of the nicer features you'll find in commercial products.
Let's start with the assumption that you're able to run antivirus software -- we'll look into what to do if this isn't the case a little later. Assuming your antivirus software is up to date, it should detect malware on your machine. Most antivirus programs have an alert page that will list each and every virus or other piece of malware it finds. You should write down the names of each malware application your software discovers.
Many antivirus programs will attempt to remove or isolate malware for you. You may have to select an option and confirm that you want the antivirus software to tackle the malware. For most users, this is the best option -- it can be tricky removing malware on your own.
If the antivirus software says it has removed the malware successfully, you should shut down your computer, reboot and run the antivirus software again. This time, if the software comes back with a clean sweep, you're good to go. If the antivirus software finds different malware, you may need to repeat the previous steps. If it finds the same malware as before, you might have to try something else
Advanced Computer Virus Removal Tips
If you can't access your antivirus software or you keep seeing the same malware pop up scan after scan, you may need to try and start your computer inSafe Mode. Many computer viruses will store files in your Windows registry folder. This folder acts like a database of instructions and tells your operating system important information about the programs you have on your computer. It can also tell viruses to activate as soon as the operating system loads. Starting your computer in Safe mode allows you to work with your machine using only the core elements of the Windows OS.
Try running your antivirus software in this mode. If you see new malware pop up, you may have hit upon your solution. Some malware exists only to download other kinds of malware and install them on your machine. If you can remove all of these applications, you'll be in good shape.
If for some reason your antivirus software can't remove the virus on its own, it's time to do a little more research. Remember when we said you should write down the names of all the malware applications that your software discovered? Here's where that comes into play. You'll need to research each of those files online using the appropriate Internet security firm. Make sure to use the same firm that produces the antivirus software you're using. That's because different firms sometimes give the same virus different names. Not all firms will refer to the same virus the same way.
Most Internet security firms will list all the files associated with a particular virus and tell you where you can expect to find those files. You may have to do some digging to find each file. Before you delete any files, you should save a backup copy of your Registry folder. If you accidentally delete the wrong file, you may make it difficult or impossible to run your computer properly.
Delete all the files associated with the malware on your list. Once that's done, you'll need to reboot your computer and run your antivirus software again. Hopefully nothing else will pop up.
You may want to update your login information for your various accounts online. Some malware has keylogging software that can send your passwords and information to a remote user. It's better to be safe than sorry..
Computer Virus Protection
There are some simple rules you can follow that will help you avoid computer viruses. Most of these fall under the category of common sense.
Don't open strange e-mail attachments or click on hyperlinks in e-mail. Virus programmers love to trick people into clicking on links that will lead them to malicious software. Let people know that you don't click on hyperlinks in e-mail unless the sender includes a description of the link and what it leads to. If your e-mail client supports autolaunch, turn it off. Otherwise you might automatically activate a computer virus just by opening the e-mail.
The same applies to other messages you might encounter. Hyperlinks in message boards, Facebookmessages or instant messages can sometimes lead to malware. Pay attention to the source of the message. Look for any unusual signs like misspellings or odd sentence structure, particularly if the person who sent you the message normally avoids errors. If you do see an odd link, you may want to let the sender know -- he or she might be the victim of a hacked account.
Don't visit questionable Web sites. This includes everything from software, music and video piracy sites to porn pages. Many current Web browsers will alert you if you try to go to a site that is known for hosting malware. Pay attention to these warnings and stay away from those sites.
Pay close attention to any windows that pop up while you surf the Web. If you see a notification claiming that you need to download the latest video driver to watch something, use caution. This is a common tactic used to distribute malware.
Run your antivirus software at least once a week. You should also make sure your antivirus software and OS remain current by downloading updates and patches on a regular basis. Most antivirus software updates at least once a week as security firms add more virus information to their databases.
Avoiding viruses might sound like a lot of work but keep in mind it's easier than fixing a computer that's been hit with a virus. Learn more about computer viruses and safe computing on the next page.