Viruses, Worms and Trojan Horses

Thanks to the evolution of the Internet, human beings are more connected than ever. Unfortunately, this connectivity has many hidden threats and dangers in the form of viruses, worms and trojan horses. These electronic contaminates can wreak havoc on any computer system or network.

You can protect yourself and your organization from becoming a victim, however, it is important that you first understand exactly what they are and how they work.

**Viruses, Worms and Trojan Horse**
Computer Viruses Computer viruses are malicious programs or pieces of code that can copy themselves and spread to other computer systems. Most viruses will attach themselves as executable files to legitimate programs such as a word or excel document. For example, a virus might attach itself to a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc on the system.	Spyware Spyware is unwanted programs that exploit infected computers for commercial gain. They can deliver unsolicited pop-up advertisements, steal personal and financial information, monitor web-browsing activity or route "HTTP" requests to advertising sites. Spyware are usually bundled as hidden components in freeware and shareware applications. If you have download and installed an application such as peer-to-peer file sharing or a screen saver, a spyware module may be actively running on your computer at this very moment without your knowledge.
Spam Spam refers to unsolicited, bulk, electronic messages sent by an unknown entity. While most commonly referred to in the context of unsolicited commercial e-mails, spam also comprises non-commercial e-mails, instant messages, chat room messages and mobile phone messages that are sent from unknown sources without the recipient's consent.	Phishing Phishing is a form of criminal activity using social engineering techniques to fraudulently acquire personal information for the purpose of identity theft. The phisher will usually send an e-mail claiming to be an established legitimate enterprise. The e-mail will direct the user to visit a web site (usually a bogus web site link) where they are asked to update personal information, such as passwords, credit cards, social security and/or bank account numbers. Once this information is entered, the phisher will use this information to commit identity theft.
Trojan Horse A Trojan horse is a malicious program acting as a benign application and will purposefully do something that the user does not expect. Trojans are not viruses since they do not replicate, but can be just as destructive. Trojan horses typically involves a server and a client. The client is cleverly disguised as significant software and positioned in peer-to-peer file sharing networks or unauthorized download websites. Once executed, the attacker (the person running the server) has a high level of control over your computer based on the attacker’s purpose.	Hacker A hacker is a person who creates and modifies computer software and hardware, including computer programming, administration, and security-related items. A hacker will access a computer system by circumventing its security mechanisms. Criminal hackers create spyware and malware for the sole purpose of committing crimes.
Malware Malware is a generic term used to describe malicious software such as viruses, Trojan horses, spyware, and malicious active content.	Worms Computer Worms are viruses that reside in the active memory of a computer and duplicate themselves. They may send copies of themselves to other computers via e-mail and chat sessions.
Virus Hoaxes Virus hoaxes are not viruses, but are usually emails that will warn you about a virus or other malicious software program. Some characteristics of a hoax would be warnings about alleged new viruses and their damaging consequences; demands that the reader forward the warning to as many people as possible; or bogus comments from officials: FBI, software companies, news agencies, etc.	Adware Adware is a legitimate, non-replicating program designed to display ads to the end user, often based on monitoring of browsing habits, and often in exchange for the right to use a program without paying for it (a take on the shareware concept).