Virus
To access to the anti-virus software directly, please click on the link Installation of McAfee Vscan Anti-Virus Software.
To get information about its usage, please click on the link How to Use the Program.
To get information on the latest virus definition files and update your anti-virus software please click on the link Update.
What's a Virus?
A virus is simply a computer program that can attach itself to programs in your computer by various ways and by running against your wishes, it may cause serious damages on your computer. Basically, a virus program is not much different from the other programs you run on your computer. Therefore, they can perform all the tasks that the operating system supports. What makes the difference about the virus program is that it is written especially to attach itself to other programs or disk boot sectors without the knowledge of the user and replicate whenever these programs are executed or those infected disks are accessed. A virus will not activate itself, unless a user executes the program or the condition(s) specified by the virus programmer takes effect. However, some viruses become active on the computer of a user not displaying their unwanted effects for some time. The viruses generally do harm by "infecting" the programs that are running on the systems or by modifying these programs. Another characteristic feature of the viruses is that they replicate and store themselves to different spaces on the memory.
Viruses may spread via floppy diskettes, network neighborhood, Internet (e-mail, downloading etc.). Viruses may cause minor problems like bothering/hindering you while you are working with the computer by displaying disturbing messages on your screen. They may produce more catasthropic results like occupying the memory or disk space of your computer and preventing an efficient access to system resources or they may destruct/erase the contents of the files you use. Moreover, they may destroy your computer programs, slow down their operation or erase all parts or the parts containing important files of your hard disk. Some viruses may behave as if they have done serious damages to the computer and give much distress to the computer novices. Some of the most famous viruses that have done much harm to computers by infecting a great deal of them in the past, but are no more effective because of the anti-virus programs written against them, are as follows:
PE_CIH (Chernobyl), "ILOVEYOU"
Virus, W97M/Thus, KRIZ, Supple,
Win32.Kriz3862, Y2KCount,
WOBBLER, LIFE STAGES.
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How do you understand when a virus infects your computer and how will you remove the viruses?
Unless you own an anti-virus program, you can only detect a virus when it displays its harmful effects. (Rarely does
it solve the problem when you perform a search by the well-known file name of a virus and then delete it.) The computer slows down
abnormally, unexpected error messages ("application error", "system fault", "missing files" etc.) appear while running Windows applications,
the computer may not respond to your commands, DOS operating system opens randomly, files cannot be opened, abnormal audio/visual
behaviours take effect or the computer performs other unwanted operations.
The only possible solution is to get yourself an anti-virus program and clean the computer with it.
However, in some cases the virus cannot be deleted properly and successfully when the system is seriously and irrevocably damaged by
the virus. If you do not have anti-virus software on your computer, you can scan your disks and diskettes via an emergency diskette that is created from an updated anti-virus software
on another computer.
If your anti-virus software cannot find any virus after the
scan operation on your computer, it does not necessarily mean that there aren't
any viruses on your computer. Always keep in mind that only those viruses that
are known and recognized by the software are detected on your system. Moreover,
the anti-virus software may not delete the viruses they detect successfully
from your computer. In this case, it is recommended that you use a different
and/or more up-to date anti-virus software.
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How will you protect your computer from viruses?
In spite of the fact that computers can be cleaned from viruses via various emergency diskettes and special programs
against viruses, you had better use programs like McAfee Anti-Virus, Norton AntiVirus, F-Prot, Dr. Solomon's Anti-Virus Toolkits in
order to prevent your computer from virus attacks in advance. These programs will alert you about any kind of virus infection on your
computer and they will disable the activities of the viruses they detect. Our university uses licensed McAfee
anti-virus program in order to evade the harmful effects of such viruses. Other than this software, you may protect your computer
by getting a free/charged anti-virus software from the web addresses as indicated below and from similar web addresses.
Most of the Anti-virus software companies release dat files and superdat files on Internet to update
their search engines and virus definition files against newly detected viruses. This process renders the anti-virus software immune to
the newly detected virus and when this virus tries to copy itself to the system, the software instantly gives alert to the user and
blocks the activity of the virus.
McAfee Vscan anti-virus program is the licensed software of our university. When it is installed on the
computers and the automatic update settings are adjusted, it starts to update the program automatically and the user interference is
not necessary anymore. By this way, the software provides a continuos protection for the computer against the newly detected viruses.
This update process may also prove effective when the computer is infected with the virus, since the program deletes it as soon as it
detects the virus. This means that the software could correct the changes the virus has done to the system. However, it is not possible
to make up for the losses caused before the update process (See How to Use the Program for detailed information).
If a computer without an anti-virus program has a virus problem, the first thing to do is to boot the computer
with an emergency diskette and clean the viruses (this emergency diskette is created from an updated anti-virus software on another computer).
The last step is to install the anti-virus program.
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The Virus Related Announcements of Computer Center
Please visit the METU
Announcements web page to see the virus related announcements of Computer
Center. Click on the Announcement
Search link. As you select the first checkbox, fill in the Keyword(s):
text box with the word "virus" and click on the Search button,
all the virus related announcements of Computer Center will be displayed on
the screen. To view the details of each announcement, you can click on the subject
links.
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Internet Web Addresses on Viruses
The following web addresses give information on viruses, up-to-date virus alerts, widespread viruses and information on how to remove them, recommended virus programs, and subscriptions to e-mail and newsgroup services.
http://www.mcafee.com
http://vil.nai.com/ (mcafee threat center)
http://www.mcafee.com/us/threat_center/glossary.html
http://www.symantec.com/avcenter/vinfodb.html
http://www.symantec.com/avcenter/
http://www.securityfocus.com/
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Some Computer Terms:
Bootable Diskette: A diskette having files with which you can boot your computer. The bootable diskettes can vary according to the operating system that is being used or according to the version of the operating system.
.EXE file : an EXE file is an executable file with an .exe extension in DOS and Windows systems. This file is in a format that the computer can directly execute. Therefore, the viruses do most of their harm on these files.
Macro: It is a list of saved commands specific to the operating system or to the program that is being used.. Once a macro virus gets onto your machine, it can embed itself in the commands of macro application and the program runs in an infinite loop.
Master Boot Record (MBR): A small program that resides in the first sector of the hard disk. It contains the file structure information of disks and diskettes. An MBR virus is a common type of virus that replaces the MBR with its own code. Since the MBR executes every time a computer is started, this type of virus is extremely dangerous.
OS-Operating System: The operating systems DOS, Win3.1, Win95, Unix, Linux, Macintosh 6.X etc. have great responsibilities like providing a suitable platform to perform the basic tasks of the computer hardware and an environment where different programs can run at the same time but do not interfere with each other.
Registry: A database used by the Windows operating system (Windows 95, 98, NT, XP) to store configuration information.
Trojan Horse: It is a destructive program which is not considered as a virus since it it does not replicate itself, but it masquerades itself as a benign application; therefore it can be just as destructive as viruses. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer.
Worm: Like Trojans, they spread via e-mails and programs like IRC and they cannot replicate themselves. They disturb the normal operation of computers.
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