History and stories
The Christmas card that jammed the world's networks
It looked like a harmless holiday greeting. Running it drew a Christmas tree made of asterisks, and then it did something else.
1 min readStory
The short version
In December 1987, a holiday greeting drew a tree on screen and quietly sent itself to everyone in the reader's address book.
The story
In December 1987, a student at the Clausthal University of Technology in Germany wrote a short program in the REXX scripting language. The person receiving it was invited to run it to see a Christmas greeting.
When run, it drew a Christmas tree in text characters with the words “A very happy Christmas and my best wishes for the next year.” Then, out of sight, it read the user’s list of contacts and sent a copy of itself to every address.
Each person who received it trusted it because it came from someone they knew. The copies multiplied across the European Academic Research Network, the BITNET academic network and IBM’s own worldwide internal network, flooding them with mail and slowing everything down.
Why it mattered
It was one of the first programs to spread by mailing itself to a person’s contacts, the same trick used years later by Melissa and ILOVEYOU. It showed that a friendly message from a familiar sender can be the one to worry about, and that a single program could slow an entire company’s worldwide network.
The lesson today
The Christmas Tree program used the same trick as the ILOVEYOU worm 13 years later and many email attacks today: it arrived from a familiar name. A message from a colleague is not proof that the colleague sent it on purpose. Unexpected attachments and links deserve a second look, even from friends.
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