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For instance getting slow or when they turn the computer on, it says that all the data is erased or when they start writing a document, it looks different, some chapters might be missing or something else abnormal has happened. The next thing usually the person whose computer might be infected with virus, panics. The person might think that all the work he had done might go missing. That could be true, but in most cases viruses have not done any harm. When some people try to get rid of viruses they delete files or they might even format the whole hard disk. That is not the best way to act when the person thinks that his computer is virus infected. Different Types of Malware : Different Types of Malware Malware is a general name for all programs that are harmful; viruses, Trojan, worms and all other similar programs Virus sources : Virus sources Viruses don not just appear, there is always somebody who has made it and they have own reason to so. Viruses are written everywhere in the world. Now when the information flow in the net and Internet grows, it does not matter where the virus is made. Most of the writers are young men. There are also few university students, professors, computer store managers, writers and even a doctor has written a virus. How viruses act : How viruses act Viruses main mission is to spread out and then get active. Some viruses just spread out and never activate. Viruses when they spread out, they make copies of self and spreading is harmful. How viruses spread out : How viruses spread out Viruses mission is to hop from program to other and this should happen as quickly as possible. Usually viruses join to the host program in some way. They even write over part of the host program. A computer is infected with a boot sector virus if it is booted from an infected floppy disk. Boot sector infections cannot normally spread across a network. These viruses spread normally via floppy disks which may come from virtually any source: How viruses activate : How viruses activate We are always afraid that viruses do something harmful to files when they get active, but not all the viruses activate. Some viruses just spread out, but when viruses activate they do very different things. Might play a part of melody or play music in the background, show a picture or animated picture, show text, format hard disk or do changes to files. There is also talk that viruses have done something to hardware like hard disk or monitor. Viruses can not do any harm to hardware but they can do harm to programs and for example to BIOS so that computer does not start after that. Usually you can start the computer from a boot diskette if the computer does not start otherwise. What are the signs of viruses : What are the signs of viruses Almost anything odd a computer may do, can blamed on a computer "virus," especially if no other explanation can readily be found. Many operating systems and programs also do strange things, therefore there is no reason to immediately blame a virus. In most cases, when an anti-virus program is then run, no virus can be found. A computer virus can cause unusual screen displays, or messages - but most don't do that. A virus may slow the operation of the computer - but many times that doesn't happen. Even longer disk activity, or strange hardware behavior can be caused by legitimate software, harmless "prank" programs, or by hardware faults. A virus may cause a drive to be accessed unexpectedly and the drive light to go on but legitimate programs can do that also. Slide 9: One usually reliable indicator of a virus infection is a change in the length of executable (*.com/*.exe) files, a change in their content, or a change in their file date/time in the Directory listing. But some viruses don't infect files, and some of those which do can avoid showing changes they've made to files, especially if they're active in RAM. Another common indication of a virus infection is a change to the reassignment of system resources. Unaccounted use of memory or a reduction in the amount normally shown for the system may be significant. In short, observing "something funny" and blaming it on a computer virus is less productive than scanning regularly for potential viruses, and not scanning, because "everything is running OK" is equally inadvisable. What to do when you find viruses : What to do when you find viruses Firstly, you should call the administrator for future action. In some cases it is not good to start you computer from hard disk, because the virus may active and then do some harm. Make sure that you should get sure that it is virus and what virus it is. It is important to know what kind of virus we are dealing with. Companies that make anti-virus programs know what different viruses do and you can go to their web pages and read about the virus you have. Slide 11: When you start you computer you should do it from a clean (non-infected) floppy diskette and after that run the virus program. The boot diskette should be write protected so that virus can not infect the boot diskette too. It is good to take a backup of the file that was infected. Virus program could do some damage to the file and that is why it is good to have a backup. It is good to let you, to know about the virus, so viruses would not spread around so much. How to protect from viruses : How to protect from viruses Best way to protect yourself is to prepare your computer against viruses in advance. One way to protect you computer is to use updated anti-virus program. When you get an email attachment, you should first check the attachment by checking the file with an anti-virus program. One can protect the computer against boot sector viruses by setting the BIOS to start from a hard disk rather than from a floppy disk. Write protection is a good way to prohibit against viruses. Write protection works well in floppy disks, Windows NT and UNIX, but not that well in Windows and Windows95. Different anti-virus programs : Different anti-virus programs There are three different kind of anti-viral packages: activity monitors, authentication or change-detection software, and scanners. Each type has its own strengths and weaknesses. Commercial anti-viral programs have a combination of the above mentioned functions. Top ten Antiviral programs : Top ten Antiviral programs Data Fellows F-Prot EliaShim ViruSafe ESaSS ThunderBYTE IBM Antivirus McAfee Scan Microsoft Anti-Virus Symantec Norton Antivirus S&S Dr S&S Dr Solomon's AVTK. Bit Defender 2008 How computer viruses have spread out around the world : How computer viruses have spread out around the world Computer viruses are a problem all over the world. The following picture tells us how many times people have accessed Data Fellows, a company that makes anti-virus program F-Prot, more than 1,672,846 per month. It means that people are interesting in virus information. One reason is that people have to deal with viruses. Viruses in not only a problem in Finland and USA, it is a problem around the world. Today's most common virus is the macro virus. Cap virus is one of the macro viruses. Last month there were 3100 Cap macro virus accesses during the last 30 days in Data Fellows. Next common virus was “Join” with 1171 accesses and third common was Pen pal Greetings with 895 accesses. Conclusions : Conclusions There are lots of viruses in the world and new viruses are coming up every day. There are new anti-virus programs and techniques developed too. It is good to be aware of viruses and other malware and it is cheaper to protect you environment from them rather then being sorry. There might be a virus in your computer if it starts acting differently. There is no reason to panic if the computer virus is found. It is good to be a little suspicious of malware when you surf in the Internet and download files. Some files that look interesting might hide a malware. Slide 19: Virus’s mission is to hop from program to other and this can happen via floppy disks, Internet FTP sites, newsgroups and via email attachments. Viruses are mostly written for PC-computers and DOS environments. Viruses are not any more something that just programmers and computer specialist have to deal with. Today everyday users have to deal with vir You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.