The E-Mail Virus

Every once in a while I get something over the internet warning me about e-mail messages with particular subject headings. One is led to believe that cataclysmic things will happen to one's hard drive if one tries to read such messages. I find that it would be in most cases next to impossible for this to happen.

Files in a computer can be treated as either data or executable programs. They actually enter the central processing unit from different paths depending on their purpose. Executable programs do something: data is information.

A virus can only be active (do something) if it is a piece of an executable; if however it is in a file that is treated only as data, it can do no harm.

In almost all cases your e-mail program will treat your messages as data. Now in addition to a main message, you may get attachments. Some of these may be out-and-out executables, and some - like a word processing file - may contain macros that could launch a virus (Melissa); but reading the main message would not run these or any other executable programs that did not exist on the system before the message arrived.

Only one way around this has come to my knowledge, and it should no longer be an issue. Some e-mail programs used to handle executable attachment names that were too long by automatically running the program and passing the remainder of the name to it to process. With the latest versions of the major e-mail program, this problem has been negated; and reading any e-mail message should be safe.

There is another issue. In order for a virus to effectively spread through the internet, it should be able to run on the computers it encounters; however each type of computer requires a different kind of executable. Not only do you have Macs and PCs but you would also get Sun workstations, Hewlett-Packard mainframes, Vax machines, Crays, and so on. To infect all of these systems, a virus would need to have a piece of executable taylored for each one; furthermore the virus creator would have to have a detailed understanding of each computer type in order to cause similar damage on all systems.

What we have here is not a computer virus but a computer rumor (sometimes called an "e-mail bomb"): it is the original message providing the "warning" - propagated not by the innards of a computer but by the users - that explodes across internet. If you have forwarded such a rumor or know someone else who has, please send a message not to spread these things further.

In saying this I acknowledge that there are some crafty people out there. If you ever do get a virus by JUST reading an e-mail message, I would be most interested in learning about it. Once you have returned your system to normal, please write to me at .

Robert G. Landrum
April 21, 1999

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