Computer Security Terms

This page provides a list of security terms with definitions.


  • Adware – Software designed to serve advertising to the computer user. It may be thought of as spyware since it usually contains the ability to gather information about the user but if it only serves ads, it is not technically spyware. Adware is legal so long as it is installed without hacking but the act of hacking is illegal in most places.
  • Attack – An attempt to gain unauthorized control of someone’s computer.
  • Backdoor – A program which allows an unauthorized user to have access to a victim’s computer.
  • Browser – A program used to view information (web pages) on the internet. Some examples include Internet Explorer, Mozilla, Firefox, Netscape Navigator, and Opera.
  • BHO – Browser Helper Object – A program written to run with a web browser to extend the functionality of the browser. An example is the Google toolbar which is a good browser helper object, but many browser helper objects may be malicious programs which may be used to take over a computer system.
  • Cookie – A simple text file which is stored on a user computer. It is used by the web page server to store information about you so it knows what to display when you visit the web site. It should only be readable by it’s creator (and therefore should not normally be a security concern), but some software flaws may allow third parties to read or modify cookies that someone else created. A cookie is used to keep track of a condition such as when a user puts an item in their shopping cart. Most cookie use is legitimate and very helpful for computer users but it may be abused when software program flaws allow it. The existence and use of cookies is not hidden from users.
  • Firewall – Firewalls, in simple terms are used to limit remote access to specific parts of the operating system or programs running on the system.  They may block incoming attempts to connect to an application or exploit a vulnerability.  Firewalls block many of the possible methods of breaking into a computer without permission.  It will help prevent hackers, viruses, worms, and trojans.  It may also block spyware from contacting the spying entity.
  • Hacker (for this discussion) – A person who deliberately attempts to manually break into other systems and use them without the knowledge of the owner.  Usually hackers exploit computer software vulnerabilities on the victim’s computer, however once they have control of a system it is not possible to be sure they are denied access again without reformatting the hard drive and re-installing the operating system.
  • Hacker Tool – A hacker tool can be any tool used by a person to gain illegitimate control over a user’s computer. It could be used to break in or installed on the victim’s computer and used to maintain control.
  • Malware – Any software that behaves in a fashon that is hostile to the computer user. This includes viruses, spyware, adware, worms, trojans, and hacker tools.
  • Packet – Part of a message or traffic being sent between two or more computers over the internet or a network.
  • Parasite – A slang term for adware and spyware which is software installed on a computer that the user did not want and was unaware of. The software is normally used for commercial purposes.
  • Port – A networking reference number used with the TCP/IP networking protocol which associates network packets (information sent over the network) with services or application programs. The port number is an indicator of which program running on a receiving computer will process the information received.
  • Process – A computer program running on a computer. A process is an actively running program.
  • Spam – Unsolicited jumk e-mail which you are not normally given an option to discontinue receiving. This type of mail is sent in bulk by to millions of e-mail addresses from a list. Sometimes an unsubscribe link is provided which may be a trick to find out if your email address is a valid address.
  • Spyware – A program that is used to gather information about a person or organization. This information may be targeted toward their internet habits such as what sites they visit but the collection of information is not necessarily limited to one area of information. The spyware program may or may not be installed with the computer user’s knowledge. Spyware is generally considered to collect information without the computer user’s knowledge. Cookies may be used to help spyware track user activity. Many free programs contain spyware such as the current popular freezip program.  One of the biggest concerns with spyware or any other potentially malicious software is that it may download other code and install it on the user’s system.  Additionally it may hide itself from the user to prevent it from being removed and make system changes which could ultimately ruin your operating system.
  • TCP/IP – The networking protocol of the internet. It is a set of standards which defines how information is sent across the internet. It supports the ability for data to reach its proper destination (address) and be processed by the proper computer program (port).
  • Trojan – A program which is usually given away for free which has a hidden purpose.  It may be some type of file such as a video that user’s may be interested in.  The user would normally install and run this program although the installation would be so simple the user would be unaware of it.  This program may or may not use a vulnerability to spread.
  • Virus – Malicious software that spreads by attaching itself to files or creating files that may be executed in some way. Usually it is sent to users as an email attachment. It may require a computer software vulnerability to spread depending on the type of program it uses to spread.
  • Vulnerability – Typically, a software bug or misconfiguration which affects the operation of an operating system or other program run on a computer allowing it to be more easily accessed using methods not intended by the program creator. Hackers, worms, viruses, and trojans use vulnerabilities to gain access to computer systems without the user’s knowledge.
  • Worm – Spreads without the user taking any action and usually exploits a bug (or vulnerability) in an operating system or some other program that may be running on a computer.  This requires a computer software vulnerability to spread. Many people’s computer systems have been infected by worms just by conecting to the internet. A presonal firewall should stop most worms.

Additional definitions and terms may be found at Definitions.