Computer viruses are small pieces of code, files, software designed to compromise the system’s security, infect the files, execute programs that distribute the virus itself or trigger other programs, makes our files unusable, send our information to others. They attack hardware by making them do undesirable tasks or make them nonresponsive. Here are the product reviews of viruses that target computer and software startup functions.
Types of viruses:
- Boot sector virus: A PC is infected with a boot sector virus if rebooted from an infected floppy disc into the floppy disc drive. Boot sector viruses used to be the most commonly found viruses several years ago and could not usually spread across a network. These viruses spread by accident through floppy disks that may come from virtually any source; unsolicited demonstration disks, brand-new software, disks used on user’s PC by salesman or engineers, new hardware, or repair hardware.
- File virus: A file virus infects other files when the program to which it is attached is run and can spread across a network. They can apply from the same sources as boot sector viruses and seeds like Internet FTP sites and bulletin boards.
- Multipartite virus: The multipartite virus corrupts boot sectors and files. An infected file often uses to infect the boot sector. Therefore, this is often one case where a boot sector virus could spread a network diagonally.
- Macro virus: A macro is an instruction that conveys out program commands manually. Many typical applications like data processing, spreadsheet, slide presentation applications use macros. Macro viruses are macro which self-replicate. If a user accesses a document bearing a viral macro and undesignedly executes this macro virus, then it can copy itself into that application’s startup files. Now, this computer is transited; a replica of the macro virus resides on this computer.
- Companion virus: A individual program file that does not adjoin itself to the actual host program. Instead, it creates a replacement program with an identical file name but with extensions that executes earlier than the original.
- Polymorphic virus: Polymorphic virus includes a separate encryption engine that stores the virus body in an encrypted format while duplicating the main body.
Computer viruses working process:
A file virus adjoins itself to a file, which is sometimes an executable application. Generally, file viruses don’t infect data files. But data files can contain embedded executable code like macros, which can exploit by a computer bug or worm authors.
Boot sector viruses modify the program, which is in the first sector of each DOCS-formatted disk. In general, a boot sector infector executes its code, then continues the PC startup process. In most cases, all write-enabled floppy disks use in that PC from then on will infect.
Multipartite viruses have a number of outlooks of both the above type of viruses. When an infected file executes, it typically infects the hard disc boot sector or partition sector and infects subsequent floppy disks use or format in the target system.
Macro viruses infect global settings files like Microsoft Word, Excel templates in order that subsequently edited documents are infected with the infective macros.
Polymorphic viruses cannot detect by trying to find an easy, single sequence of bytes in a very possibly infected file because they alter with each replication.
Companion viruses spread through a file that runs rather than the file used to run and then runs the initial file. As an example, the file MY APP.EXE may infect by creating a file called MY APP.COM.
The computer virus is an executable program that adjoins to or infects other executable programs. There are various types of infectors or viruses. One of them is system infectors that focus on computer software and hardware startup functions.