Since 2022 the Swedish agencies FRA, Must and Säkerhetspolisen jointly host an annual CTF called Undutmaning. This year’s event took place on March 21st and included a total of 24 challenges to be solved within 8 hours. The challenges span a range of categories and various levels of difficulty.
Every year Konglig Datasektionen, the Computer Science chapter at KTH Royal Institute of Technology, hosts a CTF-competition with one new challenge (window) per weekday December 1-24 at 12:15 CET. Most challenges are really more of a puzzle or word hunt than a traditional CTF-challenge. dJulkalendern is meant to cater to all students regardless of how far into their education they are, beginning with phone friendly riddle-like puzzles and then increases in difficult with each challenge. The solution to a challenge is always an English word.
Around this time last year I got curious about how electronic shelf labels (ESLs) work. They are mainly used to display the name, information and price of items in physical stores. You can easily change any of this by simply updating the e-ink display and with most of them you do not have to be in their proximity to do so. I got my hands on two from the manufacturer Pricer with the goal of getting it to display any image of my choosing.
