Christmas Tree EXEC was the first widely disruptive

computer worm A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. It wil ...

, which paralyzed several international computer networks in December 1987. The virus ran on the IBM VM/CMS operating system. Written by a student at the

Clausthal University of Technology The Clausthal University of Technology (german: Technische Universität Clausthal, also referred to as TU Clausthal or TUC) is an institute of technology ('' Technische Universität'') in Clausthal-Zellerfeld, Lower Saxony, Germany. The small publ ...

in the

REXX Rexx (Restructured Extended Executor) is a programming language that can be interpreted or compiled. It was developed at IBM by Mike Cowlishaw. It is a structured, high-level programming language designed for ease of learning and reading. P ...

scripting language, it drew a crude Christmas tree as text graphics, then sent itself to each entry in the target's email contacts file. In this way it spread onto the

European Academic Research Network The Trans-European Research and Education Networking Association (TERENA, ) was a not-for-profit association of European national research and education networks (NRENs) incorporated in Amsterdam, The Netherlands. The association was originally f ...

(EARN),

BITNET BITNET was a co-operative U.S. university computer network founded in 1981 by Ira Fuchs at the City University of New York (CUNY) and Greydon Freeman at Yale University. The first network link was between CUNY and Yale. The name BITNET origina ...

, and IBM's worldwide

VNET VNET is an international computer networking system deployed in the mid-1970s and still in current, but highly diminished use. It was developed inside IBM and provided the main email and file-transfer backbone for the company throughout the 1980s an ...

. On all of these systems it caused massive disruption. The core mechanism of the

ILOVEYOU ILOVEYOU, sometimes referred to as Love Bug or Love Letter for you, is a computer worm that infected over ten million Windows personal computers on and after 5 May 2000. It started spreading as an email message with the subject line "ILOVEYOU" ...

worm of 2000 was essentially the same as Christmas Tree, although it ran on PCs rather than mainframes, was spread over a different network, and was scripted using

VBScript VBScript (''" Microsoft Visual Basic Scripting Edition"'') is an Active Scripting language developed by Microsoft that is modeled on Visual Basic. It allows Microsoft Windows system administrators to generate powerful tools for managing comput ...

rather than

. The name was actually "CHRISTMA EXEC" because the IBM VM systems originally required file names to be formatted as 8+space+8 characters. Additionally, IBM required REXX script files to have a file type of "EXEC". The name is sometimes written as "CHRISTMAS EXEC" (adding a 9th character) to make the name more readable. The user was prompted to: "...just type CHRISTMAS..."—and this in fact launched the "worm". The worm would read the user's CMS NAMES file, which contained a list of users at remote nodes to transmit the worm to. The worm would then use the SENDFILE command to transmit the worm to those remote users, who would presumably run it, repeating the cycle. Some versions of the worm had concealed code. The actual executable part of the worm was contained in several overly long lines (more than 80 characters) that were not visible unless the user scrolled the screen to the right. The IBM 3279 color terminal would display the christmas tree with some blinking colored characters (asterisks) to represent tree lights. It displays this message when the program is run and then forwards itself to mailbox addresses contained in the user's address file.

                *
                *
               ***
              *****
             *******
            *********
          *************                A
             *******
           ***********                VERY
         ***************
       *******************            HAPPY
           ***********
         ***************            CHRISTMAS
       *******************
     ***********************         AND MY
         ***************
       *******************         BEST WISHES
     ***********************
   ***************************     FOR THE NEXT
             ******
             ******                    YEAR
             ******

__NOTOC__

References

External links

Source code
(archived) {{Hacking in the 1980s Trojan horses Email worms Rexx Hacking in the 1980s 1987 in computing

See also

References

Further reading

External links