Computer viruses are actually small programs that replicate themselves and then spread throughout your system in many ways. This is usually done without your knowledge. Such programs may copy themselves to a shared network resources or mail themselves to E-Mail Contacts that are stored in your address book.
After a Virus has infected your system, it will usually trigger itself in some way. It can launch annoying pop up windows that repeatedly place messages on your screen. It can deny you access to your data files and even change your system configuration settings. In advanced stages of infection, a virus can cause major damage to your system as it can corrupt your files and render them unreadable. It can even start deleting files as well. A virus doesn't always have to trigger itself upon infection. It can actually be programmed to launch at a specific time or on a specific date so that there will be no obvious sign of system infection. A virus usually disguises itself and may even attach itself to another file, so as to trick a user into running it.
Worms And Trojan Horses
A Worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well. The term worm was coined by John Brunner, a science fiction writer, in his 1975 novel Shockwave Rider. The hero, a talented programmer, created self-replicating computer programs that tunneled their way through a worldwide network.
A Trojan Horse is simply a malicious computer program that damages your computer system upon installation. The program claims to do one thing, such as pretending to be a game, but instead do something else when you run them. Some nasty Trojans will actually attempt to erase your hard drive. They were originally named after the historic Trojan horse used by the Greeks to conquer Troy because the first Trojan horse programs pretended to be innocent games or applications. Trojan horses have no way to replicate themselves automatically. Below you will find some of the various ways that viral related attacks can be transmitted and spread.
Some Ways That Viruses Can Be Transmitted And Spread
E-Mail Attachments: Email attachments are the most common way that ill intentioned people transmit viruses in order to infect computer users. Therefore, you should always apply caution when opening any E-Mail attachments received, especially from people who you do not know. These types of viruses are usually triggered when the attached file is opened or executed. Some viruses can even trigger themselves just by simply viewing the infected E-Mail although this is not that common. Therefore, ensure that the Anti-Virus Software you are using is set to monitor your E-Mail Program that you send and receive E-Mail with. Today's modern software programs are usually set by default to do this.
Network Shared Resources: Many viruses and worms will try to duplicate themselves by finding security loop holes in a network in order to attach themselves to a shared network resource. The most vulnerable network resource are file folders, which are shared amongst users as file access permissions are being granted. When a Virus identifies a shared folder it will attempt to copy itself into it in order to infect that Computer itself and then all computers that access the shared folder. A Worm will basically just try to replicate itself. However, it is possible to limit this risk by setting access permissions for the shared folder. If your network is set up with any shared folders, then you should have your network administrator take the appropriate action to secure them.
Removable Media: Removable Media such as Floppy Disks, Re-Writable Compact and DVD Disks, Zip Disks, USB Memory and Flash Drive are often exchanged and used from one machine to another, especially in an office. Therefore, be sure to frequently scan these removable devices to prevent infection. Today's modern Anti-Virus software will contain a built in feature where you can simply right-click on the Removal Device itself within My Computer or Windows Explorer and then choose a menu option to scan that device. In other words, if you want to scan a floppy disk, then right-click on the A: Drive within Windows Explorer and then choose a selection on the order of Scan for Viruses.
Internet Downloads: Any material downloaded from the Internet, whether they are programs, documents, music files, video files and compressed files etc., could potentially contain a virus. Therefore, be sure to scan these files first with your Anti-Virus software before you launch them. Today's modern Anti-Virus software will usually be set to scan these downloaded files for you or at least prompt you with a reminder to do so. If not then do it manually.
Document Files: Many documents and spreadsheets can contain useful macros that perform certain tasks automatically for you. However, macro viruses also exist and they use the functionality of macros to spread themselves to other files and can make alterations to the files infected.
What You Can Do To Protect Yourself
Install Anti-Virus Software and Update it Daily! Always leave it Functioning and Enabled!
Make sure your Anti-Virus Software is set to monitor your E-Mail Program that you send and receive E-Mail with!
Do not temporarily disable your Anti-Virus Software as it is too easy to forget to re-enable it!
Always keep your computer updated with the latest Security Patches! Microsoft releases them frequently as infected E-Mail Attachments may attempt to exploit program vulnerabilities.
Do not open attachments unless you are absolutely certain of the sender and the contents!
You Can Also Learn About Spyware And How To Get Rid Of It By Reading: What Is Spyware?