Computer Virus Types - Main Types of Computer Viruses
Before we get into the computer virus types, let's just quickly cover what a virus is and it's potential effects: A computer virus infects a file or program on a computer and can be coded to spread internally to other files and applications on the same computer when the infected file ro program is executed. A computer virus can also spread externally when an infected file is attached to an email or posted to a web page. Computer virus effects are wide ranging and include everything from annoying pop-ups, messages, or images to damaging effects like destruction of files, reformatting of the hard drive, or taking up large portions of a computer's system memory or storage capacity thereby affecting the computer's speed and overall performance.
There are 4 main types of computer viruses are boot sector viruses, file infector viruses, macro viruses, and multipartite viruses with boot sector and file infector being the two general terms most often associated with computer virus types. Let's take a closer look at the
There are 4 main types of computer viruses are boot sector viruses, file infector viruses, macro viruses, and multipartite viruses with boot sector and file infector being the two general terms most often associated with computer virus types. Let's take a closer look at the
different types of computer viruses and the similarities and differences between them:
Computer virus types - Boot sector virus: This type of computer virus infects the partition table or boot sector of a hard drisk or floppy disk. When a computer is booted various programs are executed to check the computer and prepare it to run for the user. The boot record is basically the content and information on a hard disk or floppy disk that initiates and controls the booting of a computer. The boot sector is the actual area on a hard disk or floppy disk that contains the boot record. A boot sector virus or boot sector infector virus places it's code into the boot sector of a computer. When an infected computer is booted the boot sector virus goes to the memory where it gains control over the operation of the computer and spreads to other drives and directories on the computer.
Computer virus types - File infector virus: This type of computer virus infects application files such as .COM and .EXE based programs. A file virus replaces or attaches itself to executable files and when activated produces the annoying or damaging results coded into the virus program. Whereas a boot sector virus is activated upon computer startup, a file infector virus is activated when the infected file is manually executed by the computer user.
Computer virus types - Macro virus: This type of computer virus is a file infector virus that is usually associated with Microsoft Word and Excel macros. A macro is a set of instructions designed to make repetitive actions more efficient, basically saving the user time by automatically performing a series of actions much faster than what the computer user could do manually. A macro virus attaches itself to a document as a macro and can be programmed to activate upon the opening, closing, saving, or deleting of the infected document. Once activated the macro virus does it's damage and if coded to do so, can copy itself into other documents thereby making it more difficult to find and delete.
Computer virus types - Multipartite virus: This type of computer virus is part file infector and part boot sector. The way a multipartite virus often works is to start off as a file virus and when activated spread into the boot sector. So not only does the multipartite virus affect the usability of the computer once booted, it also affects the actually booting of the computer and imbeds itself into the system memory thereby gaining control of the computer's operation.
How the main types of computer viruses infect a computer
In general there are two ways a virus can infect a computer: Indirect action or direct action. Indirect action viruses or resident viruses reside in a computer's system memory and can readily infect any files that are accessed. Direct action or non-resident viruses do not reside in the system memory, instead they attach themselves to a specific program and when activated infect the files and directories that are accessed via the program. Boot sector viruses are resident viruses while file viruses can be either resident or non-resident.
The different types of computer viruses can attach themselves to files or programs using various methods. A virus can infect by appending code at the end of a file or prepending code at the beginning of a file. A virus can also infect by completely overwriting the code associated with a given file. A companion virus doesn't modify or overwrite code, instead it creates a file with the same name as the file it is targeting except with a file extension that has a higher priority. For example the companion virus might be targeting ABC.exe and will therefore create ABC.com so that ABC.com, the actual virus file, runs before the normal ABC.exe file. A link virus also doesn't modify or overwrite file codes, instead it goes after the file allocation table(FAT) which controls the linking or connecting of information within a computer.
In this article we have covered the 4 main computer virus types and how those viruses can infect a computer. Keep in mind there are many variations of the 4 main types of computer viruses and those will be covered in detail through a separate section of this site in the future. Some examples include armored, bimodal, cavity, cluster, directory, encrypted, metamorphic, mutating, polymorphic, self-encrypting, self-garbling, and stealth computer virus types.
Back to Types of Malware
Back to Internet Security Suite Reviews home page
Computer virus types - Boot sector virus: This type of computer virus infects the partition table or boot sector of a hard drisk or floppy disk. When a computer is booted various programs are executed to check the computer and prepare it to run for the user. The boot record is basically the content and information on a hard disk or floppy disk that initiates and controls the booting of a computer. The boot sector is the actual area on a hard disk or floppy disk that contains the boot record. A boot sector virus or boot sector infector virus places it's code into the boot sector of a computer. When an infected computer is booted the boot sector virus goes to the memory where it gains control over the operation of the computer and spreads to other drives and directories on the computer.
Computer virus types - File infector virus: This type of computer virus infects application files such as .COM and .EXE based programs. A file virus replaces or attaches itself to executable files and when activated produces the annoying or damaging results coded into the virus program. Whereas a boot sector virus is activated upon computer startup, a file infector virus is activated when the infected file is manually executed by the computer user.
Computer virus types - Macro virus: This type of computer virus is a file infector virus that is usually associated with Microsoft Word and Excel macros. A macro is a set of instructions designed to make repetitive actions more efficient, basically saving the user time by automatically performing a series of actions much faster than what the computer user could do manually. A macro virus attaches itself to a document as a macro and can be programmed to activate upon the opening, closing, saving, or deleting of the infected document. Once activated the macro virus does it's damage and if coded to do so, can copy itself into other documents thereby making it more difficult to find and delete.
Computer virus types - Multipartite virus: This type of computer virus is part file infector and part boot sector. The way a multipartite virus often works is to start off as a file virus and when activated spread into the boot sector. So not only does the multipartite virus affect the usability of the computer once booted, it also affects the actually booting of the computer and imbeds itself into the system memory thereby gaining control of the computer's operation.
How the main types of computer viruses infect a computer
In general there are two ways a virus can infect a computer: Indirect action or direct action. Indirect action viruses or resident viruses reside in a computer's system memory and can readily infect any files that are accessed. Direct action or non-resident viruses do not reside in the system memory, instead they attach themselves to a specific program and when activated infect the files and directories that are accessed via the program. Boot sector viruses are resident viruses while file viruses can be either resident or non-resident.
The different types of computer viruses can attach themselves to files or programs using various methods. A virus can infect by appending code at the end of a file or prepending code at the beginning of a file. A virus can also infect by completely overwriting the code associated with a given file. A companion virus doesn't modify or overwrite code, instead it creates a file with the same name as the file it is targeting except with a file extension that has a higher priority. For example the companion virus might be targeting ABC.exe and will therefore create ABC.com so that ABC.com, the actual virus file, runs before the normal ABC.exe file. A link virus also doesn't modify or overwrite file codes, instead it goes after the file allocation table(FAT) which controls the linking or connecting of information within a computer.
In this article we have covered the 4 main computer virus types and how those viruses can infect a computer. Keep in mind there are many variations of the 4 main types of computer viruses and those will be covered in detail through a separate section of this site in the future. Some examples include armored, bimodal, cavity, cluster, directory, encrypted, metamorphic, mutating, polymorphic, self-encrypting, self-garbling, and stealth computer virus types.
Back to Types of Malware
Back to Internet Security Suite Reviews home page
Internet Security Reviews Blog - Visit Now
Search Computer Deals Guide Network
Computer Trends
Monthly E-Zine
- New Technology
- Industry News
- Price Trends
- Laptop Deals
- Desktop Deals
Monthly E-Zine
- New Technology
- Industry News
- Price Trends
- Laptop Deals
- Desktop Deals
More feed reader options
Bookmark or share this page
