How Computer Viruses / Malware Attack?

Computer users are facing all sorts of security threats these days, computer viruses, computer worms, hackers, phishing, spyware.  Almost every computer is challenged by more than one type of malicious attack each day.  Knowing how these malicious programs spread and work can help you avoid potential damage to your computer.
How Malware Attack

Computer viruses, worms, and Trojan horses are collectively known as malware.  They spread on the internet via email, instant messages and file sharing.  Computer viruses need a host program to run whereas computer worms are self-contained.  Both can replicate and spread in enormous rate over the internet.

Computer viruses usually cause damage to boot sector, system BIOS, software or data files.  Your system may fail to start, legitimate programs cannot run and data files are lost or corrupted.

Computer worms are usually designed to spread automatically via email program, causing major disruption of internet traffic.  Some worms can create back door to allow authorized access to your computer.

Trojan horses usually do not replicate, they appear as some innocent programs, such as free games or free screensavers.  This tricks you into downloading and running the Trojan horse.  Trojan horses can open a back door, disable antivirus program and allow the download of other malware.
How Hackers Attack

Hackers are computer users who explore networks and computers, looking for vulnerabilities and infiltrate your system without your knowledge and permission. Some people argue that hackers may not have malicious intent, they are just curious about how computer network works.  Nevertheless, unauthorized access to someone’s computer or network is not a moral act.

Malicious hackers gain access to your computer via different ways.  For examples, hackers may use keystroke logger to record your every stroke, giving them enough information to infiltrate your system.  They may hack your password by generating different combinations of numbers, letters and symbols.  Hackers also search for unprotected network or enter your system via a back door installed previously by other malware.
How Spyware Attack

Spyware are usually downloaded from web sites, email messages, instant messages or file sharing network.  Some legitimate programs may install spyware in your computer when you accept the End User License Agreement.  Spyware does exactly what its name suggests: it spies on you by collecting personal or sensitive information or tracking your browsing and shopping habit.  Some spyware programs can change your web browser's home page or install additional components to your browser without your consent.

Spyware can result in identity theft, computer slowdown and slow internet access.  Spyware should not be confused with adware.  Adware is a program that displays advertisements, usually in the form of pop up ads.  Strictly speaking, adware is not spyware if no personal information and browsing habit is collected.  It is a way for some software developers to reimburse their development cost by providing freeware to their customers.
How Spam Attack

Email spam is the electronic form of junk mail.  Most spam messages are unsolicited advertising sent to a large number of recipients.  Spam messages are not only annoying, some of them are dangerous.  Some spam messages are used to deliver Trojan horses, viruses, spyware or links to offensive web sites with inappropriate content.

A new form of spam message is used to launch phishing attack.  Phishers, pretending to be legitimate companies such as banks, financial institutes, PayPal, send out spam messages to a large number of recipients.  They usually use scare tactic and ask you to update your personal information (login ID and password, account information, etc) immediately or your account will be suspended.  Once you click on the link provided in the spam messages, you would land on phish sites which look remarkably similar to the legitimate company web sites where the phishers will steal your personal information.

Now that you know how malware, spyware, hackers and spam attack your computer, you can be more proactive in your defense.  Be careful of free download, free scan, email attachment, file sharing and don’t click on the hyperlink of spam messages.  Read the End User agreement carefully when you install any software.  Keep track of unusual inbound and outbound internet activities.  If you do all of these and install an all-in-one internet security program (antivirus, antispyware, firewall, spam control), you should be pretty safe from these malicious attacks.