So for this challenge we first need to pick up the Proxmark3 which should be laying around in the backroom of the workshop. Once obtained I watched the video from the sans 2020 vid deck on HID Hacking https://www.youtube.com/watch?v=647U85Phxgo this covered the proxmark 3 and techniques for copying and simulating cards https://github.com/Proxmark/proxmark3/wiki/lf-tag-operations. To read a card we need to stand next to the elf whos card we want to copy and open up the proxmark 3 once open we use the command lf hid read which will give us an output similar to below:
#db# TAG ID: 2006e22f0d (6022) – Format Len: 26 bit – FC: 113 – Card: 6022
Once we know how to read cards we need to know whos card to read this can be found out by visiting Fitzy Shortstack and completing the 33.6kbps mini game (pure nostalgia 🙂 ) once complete you find that santa trusts Shiny uptree so we first go up to them copy their card info with the lf hid read command and make a note of the output. Next go to the reader and stand next to it opening the proxmark where we will use the lf hid sim -r , <TAGID> command to use the copied information.
While the proxmark is still open click on the door and it will open.