While a rootkit and a virus are both types of malicious software, or malware, they are typically used to achieve different purposes in a computer attack. A rootkit typically is installed onto a computer system to either allow an unauthorized user to continue to gain access to that system or to hide the presence and activities of other types of malware. Viruses, on the other hand, are types of malware that typically are designed to attack a computer system in a very specific way and to achieve a particular goal.
Despite the fact that a rootkit and a virus are both forms of malware, they are utilized to achieve different tasks. A rootkit is a malicious program that can be installed onto a computer, at various levels within the operating system (OS), and then mask other activities. This type of program typically infects the “root” of the OS on a computer, hence the name, allowing for other activities to occur with that system that are then hidden by the rootkit. A rootkit is often used to create a backdoor entry point into a computer system for an unauthorized user to use to gain access to that system in the future or may be used to hide an infection by a virus or other type of malware.
The major difference between a rootkit and a virus is that a virus usually does not work to hide the activities of other programs or to allow access to a system. A virus is typically developed to achieve a certain effect, often by launching an attack upon a particular computer system. Though a virus can lay fairly dormant on a computer system, and remain hidden, until a particular event activates the virus, it will usually be created to launch a very specific attack on the system it infects.
There are also some major differences in how a rootkit and a virus can be removed from a computer system or OS. Viruses can often be found and removed through the user of an antivirus program, though very new viruses may elude detection for some time. A rootkit, however, can be very difficult to find, usually involving very elaborate security procedures, and nearly impossible to remove. The hard drive on a computer may need to be completely erased and the OS reinstalled to eliminate a rootkit from a computer. Ultimately, however, both a rootkit and a virus can be very destructive to a computer and efforts should be made by every computer user to avoid any type of malware.