worm -
A destructive program that replicates itself throughout a single computer or across a network, both wired and wireless. It can do damage by sheer reproduction, consuming internal disk and memory resources within a single computer or by exhausting network bandwidth. It can also deposit a Trojan that turns a computer into a zombie for spam and other malicious purposes. Very often, the terms "worm" and "virus" are used synonymously; however, worm implies an automatic method for reproducing itself in other computers. See virus, logic bomb, smartphone virus, Stuxnet, Worm.ExploreZip virus and Morris worm.
Trojan -
A program that appears legitimate but performs some illicit activity when run. It may be used to locate password information or make the system more vulnerable to future entry or simply destroy the user's stored software and data. A Trojan is similar to a virus, except that it does not replicate itself. Often sneaking in attached to a free game or other supposedly worthwhile utility, the Trojan remains in the computer doing damage or allowing someone from a remote location to take control. See Trojan dropper, wiretap Trojan, rootkit, RAT, Back Orifice, NetBus, PrettyPark, Talking Trojan and virus.
Virus -
Software used to infect a computer. After the virus code is written, it is buried within an existing program. Once that program is executed, the virus code is activated and attaches copies of itself to other programs in the computer and other computers in the network. Infected programs continue to propagate the virus, which is how it spreads.
The effect of the virus may be a simple prank that pops up a message on screen out of the blue, or it may destroy programs and data right away or on a certain date. For example, the famous Michelangelo virus contaminated the machine on Michelangelo's birthday.
Spyware -
Software that sends information about your Web surfing habits to its Web site. Often quickly installed in your computer in combination with a free download you selected from the Web, spyware transmits information in the background as you move around the Web. Also known as "parasite software," "scumware," "junkware" and "thiefware," spyware is occasionally installed just by visiting a Web site (see drive-by download).
Malware
(MALicious softWARE) Software designed to destroy data, steal information or aggravate the user. See security suite, malvertising, crimeware, virus, worm, logic bomb, macro virus, Trojan, PUP and wares.
Rootkit -
A type of Trojan that keeps itself, other files, registry keys and network connections hidden from detection. It enables an attacker to have "root" access to the computer, which means it runs at the lowest level of the machine. A rootkit typically intercepts common API calls. For example, it can intercept requests to a file manager such as Explorer and cause it to keep certain files hidden from display, even reporting false file counts and sizes to the user. Rootkits came from the Unix world and started out as a set of altered utilities such as the ls command, which is used to list file names in the directory (folder).
PUP -
(Potentially Unwanted Program) An application that is installed along with the desired application the user actually asked for. Also called a "barnacle," in most cases, the PUP is spyware, adware or some other unwanted software. However, what makes spyware or adware a PUP rather than pure malware is the fact that the end user license agreement (EULA) does inform the user that this additional program is being installed. Considering hardly anyone ever reads the license agreement, the distinction is a subtle one.
A destructive program that replicates itself throughout a single computer or across a network, both wired and wireless. It can do damage by sheer reproduction, consuming internal disk and memory resources within a single computer or by exhausting network bandwidth. It can also deposit a Trojan that turns a computer into a zombie for spam and other malicious purposes. Very often, the terms "worm" and "virus" are used synonymously; however, worm implies an automatic method for reproducing itself in other computers. See virus, logic bomb, smartphone virus, Stuxnet, Worm.ExploreZip virus and Morris worm.
Trojan -
A program that appears legitimate but performs some illicit activity when run. It may be used to locate password information or make the system more vulnerable to future entry or simply destroy the user's stored software and data. A Trojan is similar to a virus, except that it does not replicate itself. Often sneaking in attached to a free game or other supposedly worthwhile utility, the Trojan remains in the computer doing damage or allowing someone from a remote location to take control. See Trojan dropper, wiretap Trojan, rootkit, RAT, Back Orifice, NetBus, PrettyPark, Talking Trojan and virus.
Virus -
Software used to infect a computer. After the virus code is written, it is buried within an existing program. Once that program is executed, the virus code is activated and attaches copies of itself to other programs in the computer and other computers in the network. Infected programs continue to propagate the virus, which is how it spreads.
The effect of the virus may be a simple prank that pops up a message on screen out of the blue, or it may destroy programs and data right away or on a certain date. For example, the famous Michelangelo virus contaminated the machine on Michelangelo's birthday.
Spyware -
Software that sends information about your Web surfing habits to its Web site. Often quickly installed in your computer in combination with a free download you selected from the Web, spyware transmits information in the background as you move around the Web. Also known as "parasite software," "scumware," "junkware" and "thiefware," spyware is occasionally installed just by visiting a Web site (see drive-by download).
Malware
(MALicious softWARE) Software designed to destroy data, steal information or aggravate the user. See security suite, malvertising, crimeware, virus, worm, logic bomb, macro virus, Trojan, PUP and wares.
Rootkit -
A type of Trojan that keeps itself, other files, registry keys and network connections hidden from detection. It enables an attacker to have "root" access to the computer, which means it runs at the lowest level of the machine. A rootkit typically intercepts common API calls. For example, it can intercept requests to a file manager such as Explorer and cause it to keep certain files hidden from display, even reporting false file counts and sizes to the user. Rootkits came from the Unix world and started out as a set of altered utilities such as the ls command, which is used to list file names in the directory (folder).
PUP -
(Potentially Unwanted Program) An application that is installed along with the desired application the user actually asked for. Also called a "barnacle," in most cases, the PUP is spyware, adware or some other unwanted software. However, what makes spyware or adware a PUP rather than pure malware is the fact that the end user license agreement (EULA) does inform the user that this additional program is being installed. Considering hardly anyone ever reads the license agreement, the distinction is a subtle one.
