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Today's Featured Computer Term: Dingbat
A dingbat is a small picture, such as a star or a pointing finger, that can be inserted into a document. Many sets of dingbats are available as a special font. One of the most popular is Zapf dingbats, named after its creator, Hermann Zapf.
Text is entered into a document, then selected and formatted into a Dingbat font. Each text character represents a specific dingbat. For example, the letter A may be a star, the lowercase a may be an arrow.
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Today's Topic: Viruses
Worms, Trojan horses, macro viruses, boot sector viruses....it can be rather dangerous to be a computer user these days, especially if you share data with other people or download software from the Internet. The danger isn't exactly targeted towards you, but towards your data, which, in some cases, can be destroyed.
A virus is just a computer program. Like any other program, it contains instructions that tell your computer what to do. But unlike an application, a virus usually tells your computer to do something you don't want it to do, and it can usually spread itself to other files on your computer--and other people's computers.
A virus is a program or piece of code (computer instructions) that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can be hidden in executable program files posted online, secreted in mail attachments or can be distributed in other ways.
If you're lucky, a virus will execute only a benign personality quirk, such as causing your computer to make seemingly random bleeps. But a virus can also be very destructive; it could format your hard drive, overwrite your hard drive boot sector, or delete files and render your machine inoperable.
Most viruses can also replicate themselves. They can spread swiftly across open networks such as the Internet, causing billions of dollars worth of damage in a short amount of time. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
Since 1987, when a virus infected ARPANET, a large network used by the Defense Department and many universities, many antivirus programs have become available. These programs periodically check your computer system for the best-known types of viruses.
Some people distinguish between general viruses and worms. A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs.
A Trojan horse is a destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer. The term comes from a story in Homer's Iliad, in which the Greeks give a giant wooden horse to their foes, the Trojans, supposedly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their fellow soldiers to pour in and capture Troy.
A macro virus is a type of computer virus that is encoded as a macro** embedded in a document. Many applications, such as Microsoft Word and Excel, support powerful macro languages. These applications allow you to embed a macro in a document, and have the macro execute each time the document is opened. According to some estimates, 75% of all viruses today are macro viruses. Once a macro virus gets onto your machine, it can embed itself in all future documents you create with the application. Antivirus programs can protect your system against most macro viruses, although new ones are always being created that slip by the antivirus filters.
**a macro is a symbol, name, or key that represents a list of commands, actions, or keystrokes. Many programs allow you to create macros so that you can enter a single character or word to perform a whole series of actions. You can also use macros to enter words or phrases that you use frequently. For example, you could define a macro to contain all the keystrokes necessary to begin a letter -- your name, address, and a code that inserts the current date. Then, whenever you write a letter, you just press the macro key to include the letter header.
Boot sector infecting viruses are one of the most common types of viruses around. A boot sector is a special location on all disks, hard or floppy, where the Basic In/Out System (BIOS) of a computer looks during the booting of a computer for a bootable system. The boot sector of a disk stores instructions that identify the partition on a disk, contains startup files, etc.
Boot sector viruses put viral code (instructions) into the boot sector of a disk. When the computer is booted (turned on), the viral code is executed, putting the virus into memory and infecting the hard drive master boot sector.
Once infection of the master boot record of the hard disk occurs the virus is run in memory each time the computer is booted from the hard drive. All disks used on the computer from that point forth have their boot sector infected with the virus code. This leads to proliferation to other systems or reinfection of a cleaned computer at a later date.
Tips for Avoiding Viruses:
Install an antivirus program and keep it updated. An antivirus program is a utility that searches a hard disk for viruses (known virus codes) and removes any that are found. Most antivirus programs include an auto-update feature that enables the program to download profiles of new viruses so that it can check for the new viruses as soon as they are discovered.
Don't accept disks from friends. Even well-meaning people can pass along contaminated files.
Don't download Internet files, especially from newsgroups. If you must do so, take your chances with large commercial sites, which are more likely to check files for viruses before posting them.
Don't open executable files attached to e-mail. Just delete the messages.
If you don't know the sender of an e-mail attachment, don't open it. Delete it right away.
If you download executable files from the Internet, Usenet newsgroups, or FTP sites, scan them in a safe area before executing.
Things to Remember:
You can only get a virus by executing an infected program or booting from an infected disk.
You cannot get a virus simply by being on the Internet or an online service. You will only become infected if you download an infected file and execute that file.
You cannot get a virus by reading an email. You will only become infected if you download an infected file and execute that file.
Make sure you have at least two backups for all of your files. Backups are essential not only to safely recover from virus infections, but also to recover from the other threats to your data. |
