Windows Security Tutorials - Herong's Tutorial Examples - Version 3.00, by Dr. Herong Yang
What Is Malware (Malicious Software)?
This section provides a quick introduction of malware (Malicious Software), which can be divided into sub categories like: Adware, Spyware, Trojan, Virus, etc.
What Is Malware (Malicious Software)? A Malware (Malicious Software) is a software designed to do harmful things to your computer or to you as a user of your computer. Harmful things include damaging your computer system, disrupting other software operation, gathering your private information, distributing unwanted advertisements, etc.
Malware is a general software category, and can be divided into many sub-categories such as those listed below:
Virus - A virus is a type of malware that, when executed, replicates by inserting copies of itself (possibly modified) into other computer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected". Viruses often perform some type of harmful activity on infected hosts.
"Stoned" is a good example of early computer boot sector viruses. It was created in 1987 by a university student in New Zealand and became very common and widespread in the early 1990s. When a computer infected by the virus started, there was a one in eight probability that the screen would declare: "Your PC is now Stoned!".
Worm - A worm is a type of malware that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program.
"Morris Worm" is a good example of computer worms. It was written in 1988 by a student at Cornell University exploiting known vulnerabilities in Unix sendmail, finger, rsh/rexec and weak passwords to infect and replicate on the Internet.
Trojan - A Trojan is a type malware that, when executed, carries out actions determined by the nature of the Trojan, typically causing loss or theft of data, and possible system harm. The term is derived from the story of the wooden horse used to trick defenders of Troy into taking concealed warriors into their city in ancient Greece, because computer Trojans often employ a form of social engineering, presenting themselves as routine, useful, or interesting in order to persuade victims to install them on their computers.
"Beast" is a good example of computer Trojan Horses. It was written in Delphi programming language in 2002 and became very popular. It was using the injection method to inject viruses into specific process, commonly "explorer.exe" (Windows Explorer), "iexplore.exe" (Internet Explorer), or "msnmsgr.exe" (MSN Messenger) to steal information and give control to its author of your computer.
Spyware - A spyware is a type of malware designed to gather information about a person or organization without their knowledge and that may send such information to another entity without the consumer's consent, or that asserts control over a computer without the consumer's knowledge.
"CoolWebSearch" is a good example of computer spyware. It first appeared in May 2003. When installed on a computer, it can change web browser homepage to coolwebsearch.com, and although originally thought to only work on Internet Explorer, recent variants affect Mozilla Firefox as well as others like Google Chrome. It can also create pop-up ads that redirect to other websites including pornography sites, collect private information about users and slow the speed of infected computers.
Adware - A adware is a type of malware designed to present unwanted advertisements to the user of a computer. The advertisements produced by adware are sometimes in the form of a pop-up or a background audio play.
"180SearchAssistant" is a good example of computer adware. It was developed by 180Solutions and first released in 2004. When installed, it monitors the contents of Web browser windows. It opens the Web pages of partner Web sites as advertisements when it sees certain keywords in search or shopping browser windows.
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