1. Computer Applications Unit B
Viruses, Trojans, and Other Security Threats

2. “BUG”
A “bug” is a software error or flaw that causes the software to behave in unexpected or unusual ways.
The term was coined in 1946 by Grace Cooper when an actual moth was discovered stuck in the wires of a computer.
When asked about progress of the machine, Cooper said, “I don’t know, they’re still getting the bugs out”, leading to our term today.
Debugging is the process of removing said bugs from programs which cost about $59 billion annually of the US economy.

3. Malware
Short for malicious software, malware is used interrupt computer operations, gather sensitive information, or gain private computer access.
Malware has many varying forms, and some are even used by legitimate companies to gather analytical data on their users.

4. Rootkit
A stealthy type of software that is designed to hide the existence of certain processes or programs from normal methods of detection.
The name comes from the concatenation of “root” (the privileged account on UNIX operating systems) and kit (referring to the software components).
Difficult to detect due to the fact that software is intended to evade any software that is intended to find it.
Removal is nearly impossible and usually involves reinstallation of the Operating System.
Rootkits were famously made aware to the general public with the Sony BMG copy protection scandal.

5. Spyware
Spyware is software that aids in gathering information about a person or organization without their knowledge and may send it to another entity without consent.
Usually classified into four types: system monitors, Trojans, adware, and tracking cookies.
When used for malicious purposes, its presence is typically hidden from the user and can be difficult to detect.
Spyware can change computer settings, interfere with user control, and even collect almost any data such as Internet surfing habits, logins, and bank information.

6. Adware
Adware, or advertising-supported software, is any software package which automatically renders advertisements in order to generate revenue for its author.
The ads are usually present in the user interface of the software or are present during the installation of the software.
Though legitimate, the malware version usually is unwanted, and presented as a pop-up.
Usually detectable with anti-adware programs.

7. Keystroke Logging
Often referred to as keylogging, keystroke logging is the action of recording the keys struck on a keyboard, without the user unaware that their actions are being monitored.
Various methods are available for combatting keystroke logging ranging from auto-fill on a web browser to using software to combat loggers.

8. Scareware
Scareware comprises several classes of scam software that is of limited or no benefit and is sold using unethical practices.
Using social engineering to cause the user shock, anxiety, or the perception of a threat, the software tricks the user into doing a desired action.
Often bundled with a message that the computer is bundled with a fake virus and that the user needs to download a fake anti-virus program to remove it.
This fake software is often malware by its own right.

9. Computer Virus
A virus is a type of malware then when executed, replicates by inserting copies of itself into other computer programs, data files, and other areas of the hard drive.
Viruses often use up vital system resources, accessing private information, corrupt data, and more.
Various motives are behind the creation of viruses, causing billions of dollars of damage each year.
No anti-virus program can currently detect all computer viruses, though research to more effectively detect viruses is being developed.
Viruses are not exclusive to Windows, but target Windows machines due them having the greatest share of the market.

10. Computer Worm
A worm is a standalone malware program that replicates itself to spread to other computers.
Unlike a virus, it does not need to be attached to another program.
Worms often congest networks, consuming bandwidth, but often do not infect the computers they pass through.
Worms often install backdoors, allowing creation of a zombie computer.

11. Zombie
A zombie computer is one that has been compromised by a hacker, virus, or Trojan and can then be used to perform malicious tasks.
Often used to perform spam or denial-of-service-attacks.
The user is usually unaware that their computer has been affected.

12. Denial of Service Attack
A DOS (denial of service) attack is an attempt to make a machine or network resource unavailable to its intended users.
Generally, the effort is temporarily or indefinitely interrupt or suspend services of a host connected to the internet.
DOS attacks usually target a server, causing server overload, preventing the server from being able to provide its service.
DOS attacks are considered to be almost universal violations of acceptable use by all Internet Service Providers, laws of individual nations, and the Internet Architecture Board’s Internet proper use policy: in a nutshell, no one endorses them.

13. Trojan Horse
A Trojan Horse, or Trojan, is a hacking program that is non-replicating malware which gains privileged access to the operating system while appearing to do a desirable function, but instead creates a backdoor allowing unauthorized access to the computer.
The backdoors created are invisible to average users, but may cause the computer to slow.
Unlike viruses, Trojans will not attempt to spread to other files, or harm the computer.
The name comes from the story in Greek Mythology, where the software presents itself as a harmless gift, in order to persuade victims to install the Trojan on the computer.