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Type Of Computer Virus Pdf

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Name Type Description Manufacturer Location Keywords SPSS Statistical A statistical Package, designed for analysing data. IBM SPSS Staff WTS 2000 Cluster WTS. See the latest information on computer virus attacks and their removal. McAfee is the leader in internet security and virus detection. Keep up to date on the most. Common Types of Computer Viruses and Other Malicious Programs. What is Computer Virus Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation. A virus might corrupt or delete data on your computer, use your e mail program to spread itself to other computers, or even erase everything on your hard disk. Computer viruses are often spread by attachments in e mail messages or instant messaging messages. That is why it is essential that you never open e mail attachments unless you know who its from and you are expecting it. Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files. Screenshot.31920.1000000.jpg' alt='Type Of Computer Virus Pdf' title='Type Of Computer Virus Pdf' />Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download. How Computer Viruses Work Here is the general way that viruses work An infected program is run. This is either a program file in the case of a file infecting virus or a boot sector program at boot time. In the case of a Microsoft Word document the virus can be activated as soon as the document that contains it is opened for reading within Microsoft Word. If the NORMAL. DOT document template is infected and this is the most common target of these viruses then the virus may be activated as soon as Microsoft Word is started up. The infected program has been modified so that instead of the proper code running, the virus code runs instead. This is usually done by the virus modifying the first few instructions to jump to where the virus code is stored. The virus code begins to execute. The virus code becomes active and takes control of the PC. There are two ways that a virus will behave when it is run direct action viruses will immediately execute, often seeking other programs to infect andor exhibiting whatever other possibly malicious behavior their author coded into them. Many file infector viruses are direct action. In contrast, memory resident viruses dont do anything immediately they load themselves into memory and wait for a triggering event that will cause them to act. Many file infectors and all boot infectors do this boot infectors have to become memory resident, because at the time they are executed the system is just starting up and there isnt that much interesting for them to do immediately. What exactly the virus does depends on what the virus is written to do. Their primary goals however include replication and spreading, so viruses will generally search for new targets that they can infect. For example, a boot sector virus will attempt to install itself on hard disks or floppy disks that it finds in the system. File infectors may stay in memory and look for programs being run that they can target for infection. Malevolent viruses that damage files or wreak havoc in other ways will often act on triggers. There are viruses that will only activate on particular days of the year such as the infamous Friday the 1. Some viruses do nothing other than trying to maximize their own infection to as many files and systems as possible. Most Common Types of Viruses and Other Malicious Programs. Resident Viruses This type of virus is a permanent which dwells in the RAM memory. From there it can overcome and interrupt all of the operations executed by the system corrupting files and programs that are opened, closed, copied, renamed etc. Examples include Randex, CMJ, Meve, and Mr. Klunky. 2. Multipartite Viruses. Multipartite viruses are distributed through infected media and usually hide in the memory. Gradually, the virus moves to the boot sector of the hard drive and infects executable files on the hard drive and later across the computer system. Direct Action Viruses The main purpose of this virus is to replicate and take action when it is executed. When a specific condition is met, the virus will go into action and infect files in the directory or folder that it is in and in directories that are specified in the AUTOEXEC. BAT file PATH. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted. Overwrite Viruses Virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected. Fever Softball Whc there. Instagram For Pc Windows 7. The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content. Examples of this virus include Way, Trj. Reboot, Trivial. 8. D. 5. Boot Virus This type of virus affects the boot sector of a floppy or hard disk. This is a crucial part of a disk, in which information on the disk itself is stored together with a program that makes it possible to boot start the computer from the disk. The best way of avoiding boot viruses is to ensure that floppy disks are write protected and never start your computer with an unknown floppy disk in the disk drive. Examples of boot viruses include Polyboot. B, Anti. EXE. 6. Macro Virus Macro viruses infect files that are created using certain applications or programs that contain macros. These mini programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. Examples of macro viruses Relax, Melissa. A, Bablas, O9. 7MY2. K. 7. Directory Virus Directory viruses change the paths that indicate the location of a file. By executing a program file with the extension. EXE or. COM which has been infected by a virus, you are unknowingly running the virus program, while the original file and program have been previously moved by the virus. Once infected it becomes impossible to locate the original files. Polymorphic Virus Polymorphic viruses encrypt or encode themselves in a different way using different algorithms and encryption keys every time they infect a system. This makes it impossible for anti viruses to find them using string or signature searches because they are different in each encryption and also enables them to create a large number of copies of themselves. Examples include Elkern, Marburg, Satan Bug, and Tuareg. File Infectors This type of virus infects programs or executable files files with an. EXE or. COM extension. When one of these programs is run, directly or indirectly, the virus is activated, producing the damaging effects it is programmed to carry out. The majority of existing viruses belongs to this category, and can be classified depending on the actions that they carry out. This type of viruses consists of encrypted malicious code, decrypted module. The viruses use encrypted code technique which make antivirus software hardly to detect them. The antivirus program usually can detect this type of viruses when they try spread by decrypted themselves. Companion Viruses Companion viruses can be considered file infector viruses like resident or direct action types. They are known as companion viruses because once they get into the system they accompany the other files that already exist. In other words, in order to carry out their infection routines, companion viruses can wait in memory until a program is run resident viruses or act immediately by making copies of themselves direct action viruses. Some examples include Stator, Asimov. Terrax. 1. 06. 91.

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