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What is a Computer Worm?
What's a computer worm? Computer worms are like viruses and Trojan Horses, but have different effects and intentions. Advice: Know their differences!
A worm is a malicious code capable of reproducing itself... It can infect and spread from one computer to another. Worms have been around since the use of the internet became widespread. "As the public relies increasingly on high-speed electronic communications, email attachments, and peer-to-peer file sharing programs, viruses and worms will continue to spread." 
Be aware! Various reports on the Internet show that computer worms are distributed to thousands of unsuspected PC users each year.
Warning! Sending a computer worm is violation of the 1986 Computer Fraud and Abuse Act.
What does a computer worm do? A computer worm will replicate itself (unlike a Trojan Horse) from system to system without the use of a host file (in contrast to viruses), spreading itself across unprotected networks. Worms reproduce not by infiltrating files but by infiltrating systems. They operate through networks and work as stand-alone programs; this means that they do not attach or embed themselves in other programs (like viruses). Also, worms are hard to track, are often disguised, and can spread easily and rapidly via email attachments. Worms may or may not depend on the recipient opening an email attachment to infect a system; in fact they don't require human intervention to propagate.
Who sends out computer worms? And, why? Worms are sent for either nonmalicious or malicious purposes; they are sent by malicious users or hackers.
What happens to a PC that's infected by a worm? When a worm infects a PC, it will write a malicious code to the computer and begin replicating itself. Worms tend to overwrite files and create hidden copies of the originals. They can infect a computer as well as the internet.
Possible effects of a worm? Worms are capable of spreading from one system to another until they reach their target PC; by doing so, they can cause system failures or damage, and shutdown or disconnection from the Internet.
Who's at risk? Poorly protected computers will likely be susceptible to worms.
How do I know I have a worm? Computers that are infected by a worm will noticeably see a decrease in computer performance as well as a decrease in Internet connection speed. Additionally, worms have been known to modify security-related application settings; that is, being able to turn off antivirus or anti-spyware protection. It's best to look for these types of signs.
How do I prevent a worm from entering my PC? In order to avoid a computer worm, it's best to have installed a malicious software removal tool or scanning utility. The best way to know if you are infected by a worm is to run a good antivirus product or security suite like Norton Internet Security 2010. Alternative: Try Avast, it's a good free virus and worm removal tool. Also, it's important for PC users to protect their operating system's directory executable files, because worms are known to appear inside files (often even in Word or Excel documents).
Ways to protect the PC:
- Set up a firewall for the PC
- Install the newest and latest antivirus (and worm) product or security suite
- Keep the operating system up-to-date with the latest security upgrades
- Use strong passwords on your PC and network
- Don't open emails when you are unsure of the sender
- Ensure to back up all important PC files
* Best advice:
- Practice Safe Computing!
- Be aware of the latest Cyber Security Threats!
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An Example of a Computer Worm: The Conficker Worm
Some past examples of Computer Worms were...
- Melissa - a mass-mailing worm (appeared in 1999)
- ILoveYou - a very destructive worm that had a text email message containing the words “I love you." (appeared in 2000)
- MyDoom - was a very fast-spreading worm that caused worldwide Internet performance slowdown (appeared in 2004)
Many more worms have occurred over the years, but one of the latest ones is the Conficker Worm (see image and reference link) that appeared in late 2008. It had a great impact on Microsoft Windows operating systems. The Conficker worm drew widespread attention from the security community and the media. It's the one computer worm that is still being talked about today.
Researchers estimated that millions of computers worldwide had been infected by the Conficker worm. Today, it has revealed 5 threats (labeled as Win32/Conficker.A/B/C/D/E). If you are faced with the Conficker worm, here's what you can do to help yourself; obtain, "Free Conficker Virus Removal Tools."
-  CCIPS, John G. Malcolm - Testimony Case (Computer Crime)
Practice Safe Computing: http://www.claymania.com/safe-hex.html
- Cyber Security Threats: http://www.us-cert.gov/cas/alerts/index.html
- Computer Fraud and Abuse Act: http://www.cybercrime.gov/ccmanual/01ccma.html
- Image: Microsoft - Protect yourself from the Conficker Worm virus