The battle was intense, the atmosphere nerdy: CTF TU Delft Team wins SURFcert's Capture the Flag 2025

59 challenges in IT security

The anniversary edition of Capture the Flag kicked off live once again this year. On 3 December at 09:30, the 32 teams gathered at the digital starting line, ready to compete for one goal: the coveted SURFcert CTF game flag.

The theme of this tenth edition was Computer History: a nostalgic yet deceptively challenging journey through the evolution of IT security. In just 6 hours, participants faced 59 brain-twisting challenges, ranging from physical puzzles to crypto tasks. The competition was intense, the atmosphere delightfully nerdy, and the mission clear: who would earn the most points to claim the physical flag?

The 59 challenges were broadly divided into categories: from crypto and encoding to physical, binary, forensics, networking, miscellaneous and obviously nerd. A total of 8250 points were up for grabs for the teams that dared to bite into the puzzles. Each CTF edition highlights a different aspect of cybersecurity. This year, the focus was clearly on encoding, crypto and forensics, requiring participants not only to think fast but also to dig deep into their knowledge.

Strategically exciting battle

CTF TU Delft Team took a huge spurt in solving the questions right from the start. After the first half of game time, the battle for the CTF game flag was mainly between the teams CTF TU Delft Team, I'm not a Robot (last year's winner!), CTF Team TU Delft and http::ass. In the last half-hour, the scoreboard went into 'freeze'. The battle continued, but the standings were no longer updated live for everyone. This was meant for the strategic players and created extra tension until the end.

During the freeze, little changed in the ranking of the teams. Thus, CTF TU Delft Team also took victory in the end. Second was team CTF Team TU Delft and third place - with a surprising final sprint - went to team SurVU.