June 2000 Bulletin

Tactics to avoid computer virus attack

Scan everything, be wary of unsolicited attachments

The love bug virus that infected computers in at least 20 countries around the world, causing billions of dollars in damage last month exposed the vulnerability of corporations, governments and individuals.

A computer virus can be introduced to a computer system along with any software program. For Internet users, this threat can come from downloading files through FTP (file transfer protocol) or from e-mail attachments.

When a virus is introduced to a computer system, it can attach itself to, or sometimes even replace an existing program. When the user runs the program in question, the virus also is activated. This usually happens without the user being aware of it.

A virus program contains instructions to initiate some sort of "event" that affects the infected computer. For example:

There are many types of computer viruses, including:

File virus. Most viruses fall into this category. A virus attaches itself to a file, usually a program file.

Boot Sector. The viruses infect floppy and hard drives. The virus program will load first, before the operating system.

Trojan Horse. These programs appear to be something other than what they are, for example a "virus" that is disguised as a legitimate software program.

The love bug virus is technically known as a worm. This software is written to spread automatically through e-mail.

On May 4, computer users saw e-mail that said ILOVEYOU. The note asked the user to open the attached LOVELETTER. When they clicked on the attachment LOVE-LETTER-FOR-YOU.txt.vbs, the virus was activated. The virus spread by mailing itself to all the e-mail addresses in the victims’ address books. By the second day, at least 10 variants of the virus were spreading with subject lines ranging from "Mother’s Day order confirmation" and "Very Funny" to "virus alert" messages.

Last year’s Melissa virus that caused havoc with an estimated 300,000 computers, limited copies of itself to 50 people in an address book. The love bug virus could spread itself to hundreds, even thousands of other addresses.

Major corporations such as Microsoft Corp., Ford Motor Co and Safeco shut down their e-mail systems. U.S. government officials said the virus e-storm contaminated classified internal e-mail systems. The media reported the virus was detected in the computers of the super-secret National Security Agency.

The love bug virus caused some damage by destroying files that stored visual images and music by writing copies of the virus over them.

Estimates of damage caused by the virus could rise to $10 billion. An estimated 45 million people received the virus on the first day of the assault.

How to protect yourself

There are many types of anti-virus software, employing several technologies. A common type of anti-virus tool is a "scanner".

Scanners examine every file on a specific disk drive, looking for known virus "signatures". Every virus has a unique signature, which is a string of software code. The drawback to scanners, includes the inability to detect new viruses, and the requirement that the user determines when to initiate the virus scanning process.

Other types of anti-virus tools include those that will run continuously on a system, and those that will run every time the machine is booted.

Having up-to-date anti-virus software will protect you against known macro viruses, but there are additional steps you can take to prevent your computer from getting infected, and to prevent you from spreading any macro virus that you may get.

Scan everything—documents and files on a floppy or ZIP disk and new software diskettes.

Be cautious about opening attachments. An e-mail message itself cannot contain a virus, however, attachments that are sent along with e-mail messages can contain viruses.

Don’t open any document or image file without knowing what it is. Write the sender and ask about the contents of the file.

Back up data on a regular basis.

Source: © 1997 Network Solutions

Special Report: See Digital Imaging article

Computer Link welcomes suggestions about future topics for the column and questions about the use of computers in orthopaedic practice. Send your suggestions to the Bulletin at AAOS, 6300 N. River Rd., Rosemont, Ill. 60018.

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