...The IBM Christmas Virus

The Christmas virus infected IBM's network extending throughout the United
States, and to many of 140 other nations.  The virus first emerged on EARN,
the European equivalent of BITNET, networks that link universities in North
America and Europe.  The infection originated from a West German law student,
a user of EARN who says that he only wanted to send a Christmas greeting to his
friends in the form of a graphic of a festive tree that would appear 
mysteriously on their screens.  But the virus ran amok around the world, 
passing through electronic mail gateways, crossing the Atlantic by 
communications satellite and infecting the IBM internal network.

The Christmas virus spread so rapidly without detection because it looked
up names and address files on the computers it reached and then replicated by
sending itself on to these addresses.  victims called up the infected program 
by keying the word Christmas when their electronic mailboxes indicated that
festive messages were waiting for them from colleagues with whom they were
used to corresponding.  Disguising a virus program so that it looks like a
legitimate message from a friend or associate is now a popular method of 
spreading infection.  There were extensive memory-consuming graphics in the
Christmas virus, so it soon began to seize up systems as it proliferated.  IBM
effectively had to close down its 350,000 terminal internal mail network to 
clear the virus out.  The functioning of the world's largest computing company
was seriously affected for nearly three days.


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"Computer Viruses, Worms, Data Diddlers, Killer Programs, and Other Threats
To Your System: What They Are, How They Work, And How To Defend your PC, Mac,
Or Mainframe."  McAfee, John and Colin Haynes. (C) 1989 by John McAfee and
Colin Haynes.  St. Martin's Press.  p. 99.
