Written by a student at the Clausthal University of Technology in the REXX scripting language, it drew a crude Christmas tree as text graphics, then sent itself to each entry in the target's email contacts file.
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Its core mechanism was essentially the same as the ILOVEYOU worm of 2000 - although running on mainframes rather than PCs, spreading over a different network, and scripted using REXX rather than VBScript.
Christmas | One Tree Hill | One Tree Hill (TV series) | A Christmas Carol | Christmas Eve | Christmas Island | tree | Christmas music | Christmas tree | Herbert Beerbohm Tree | A Christmas Story | Porcupine Tree | Have Yourself a Merry Little Christmas | Christmas Oratorio | How the Grinch Stole Christmas | The Joshua Tree | The Hanging Tree | How the Grinch Stole Christmas! | Christmas lights | Quebracho tree | Mickey's Christmas Carol | Joshua Tree National Park | Under the Yum Yum Tree | The Nightmare Before Christmas | Merry Christmas Baby | Last Christmas | I'll Be Home for Christmas | Happy Tree Friends | Christmas lights (holiday decoration) | Christmas card |
However, in practice this advice is not enough – "known trusted sources" were the senders of executable programs creating mischief and mayhem as early as 1987 (with the mainframe-based Christmas Tree EXEC), so since the ILOVEYOU and Anna Kournikova worms of 2000 and 2001 email systems have increasingly added layers of protection to prevent potential malware – and now many block certain types of attachments.