Virus & Spyware Definitions
A computer virus attaches itself to a program or file so it can spread from one computer to another, leaving infections as it travels. Much like human viruses, computer viruses can range in severity; some viruses cause only mildly annoying effects while others can damage your hardware, software, or files. Almost all viruses are attached to an executable file, which means the virus may exist on your computer but it cannot infect your computer unless you run or open the malicious program. It is important to note that a virus cannot be spread without a human action, (such as running an infected program) to keep it going. People continue the spread of a computer virus, mostly unknowingly, by sharing infecting files or sending e-mails with viruses as attachments in the e-mail. |
Any software that covertly gathers user information through the user's Internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of freeware or shareware programs that can be downloaded from the Internet; however, it should be noted that the majority of shareware and freeware applications do not come with spyware. Once installed, the spyware monitors user activity on the internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers. Spyware is similar to a Trojan horse in that users unwittingly install the product when they install something else. A common way to become a victim of spyware is to download certain peer-to-peer file swapping products that are available today. Aside from the questions of ethics and privacy, spyware steals from the user by using the computer's memory resources and also by eating bandwidth as it sends information back to the spyware's home base via the user's internet connection. Because spyware is using memory and system resources, the applications running in the background can lead to system crashes or general system instability. Because spyware exists as independent executable programs, they have the ability to monitor keystrokes, scan files on the hard drive, snoop other applications, such as chat programs or word processors, install other spyware programs, read cookies, change the default home page on the Web browser, consistently relaying this information back to the spyware author who will either use it for advertising/marketing purposes or sell the information to another party. Licensing agreements that accompany software downloads sometimes warn the user that a spyware program will be installed along with the requested software, but the licensing agreements may not always be read completely because the notice of a spyware installation is often couched in obtuse, hard-to-read legal disclaimers. |
Adware is a form of Spyware that collects information about the user in order to display advertisements in the Web browser based on the information it collects from the user's browsing patterns. |
Short for Malicious Software, software designed specifically to damage or disrupt a system, such as a virus or a Trojan horse. |
A Worm is similar to a virus by its design, and is considered to be a sub-class of a virus. Worms spread from computer to computer, but unlike a virus, it has the ability to travel without any help from a person. A worm takes advantage of file or information transport features on your system, which allows it to travel unaided. The biggest danger with a worm is its ability to replicate itself on your system, so rather than your computer sending out a single worm, it could send out hundreds or thousands of copies of itself, creating a huge devastating effect. One example would be for a worm to send a copy of itself to everyone listed in your e-mail address book. Then, the worm replicates and sends itself out to everyone listed in each of the receiver's address book, and the manifest continues on down the line. Due to the copying nature of a worm and its ability to travel across networks the end result in most cases is that the worm consumes too much system memory (or network bandwidth), causing Web servers, network servers, and individual computers to stop responding. In more recent worm attacks such as the much talked about .Blaster Worm., the worm has been designed to tunnel into your system and allow malicious users to control your computer remotely. |
A Trojan Horse at first glance will appear to be useful software but will actually do damage once installed or run on your computer. Those on the receiving end of a Trojan Horse are usually tricked into opening them because they appear to be receiving legitimate software or files from a legitimate source. When a Trojan is activated on your computer, the results can vary. Some Trojans are designed to be more annoying than malicious (like changing your desktop, adding silly active desktop icons) or they can cause serious damage by deleting files and destroying information on your system. Trojans are also known to create a backdoor on your computer that gives malicious users access to your system, possibly allowing confidential or personal information to be compromised. Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-replicate. |
The registry is the part of an operating system which records the relationship between hardware, memory space and addressing. In general terms it is a database which stores settings and options for the operating system, especially for Microsoft Windows 32-bit versions. It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to "Control Panel" settings, or file associations, system policies, or installed software, the changes are reflected and stored in the registry.On Windows 9x computers, an older installation can have a very large registry that slows down the computer's startup and can make the computer unstable.The registry can be edited in Microsoft Windows by running regedit.exe in the Windows directory. WARNING: editing the registry can cause irreversible damage unless you are sure of what you are doing. Many optimization and "hacking" tools are available to modify this portion of the Windows operating system. It is preferable to use one of the (many) registry cleaners available.A simple implementation of the current registry tool appeared in Windows 3.x, called the "Registration Info Editor". This was basically just a file extension database used to associate files when double clicked.Windows NT introduced permissions for Registry editing. Windows 2000 incorporated both the Windows 9x REGEDIT.EXE program and NT's REGEDT32.EXE program. REGEDIT.EXE had a left-side tree view that began at "My Computer" and listed all loaded hives. REGEDT32.EXE had a left-side tree view, but each hive had its own window, so the tree displayed only keys. REGEDIT.EXE represented the three components of a value (its name, type, and data) as separate columns of a table. REGEDT32.EXE represented them as a list of strings. REGEDIT.EXE was written for the Win32 API and supported right-clicking of entries in a tree view to adjust properties and other settings. REGEDT32.EXE was written for the NT 3.x API and required all actions to be performed from the top menu bar. Because REGEDIT.EXE was directly ported from Windows 98, it did not support permission editing (permissions do not exist on Windows 9x). Therefore, the only way to access the full functionality of an NT registry was with REGEDT32.EXE, which many considered to be inefficient and out-of-date. Windows XP was the first system to integrate these two programs into one, adopting the REGEDIT.EXE behavior with the additional NT functionality. |
Definition of a Computer Virus 
Spyware
