Belgian Cyber Security Challenge CTF: A Junior’s View

The Belgian Cyber Security Challenge is a Capture-The-Flag game that’s focused on cybersecurity. The event is organised by Toreon’s friends NVISO.

Wednesday 10 am started my team’s 32 hour adventure; capturing as many flags as we could possibly find.

10:30 am: first blood! After half an hour we already found a first flag that placed us in the top five on the scoreboard.

12:00 am: finally a second flag we could submit to the platform!
As all team members finished working, we gathered on voice chat to discuss strategies and started brainstorming around the challenges. At first sight it seemed like NVISO had stepped up their game, since the challenges last year were not as difficult as in this edition.

6:00 pm: it had been six hours since we last submitted a flag. Other teams caught up with us and we started to lose all hope. But then we started to understand how certain challenges were built and where we should look for the flags.

6:30 pm: new flag, back on track! We were frustrated since a lot of people had found the flag of the so called ‘ModBusted’ challenge, inspired by Industrial Control Systems. Two of our team members had already done some research on ICS-systems in the past but we just couldn’t find that one easy flag that everyone else did.

07:45 pm: Yeahaa! We found it! This flag took us from 61th place all the way back to 22nd! At this point we were so happy and filled with new hope.

09:30 pm: We lost too much time on this one. This was probably the last easy one we found.

11:00 pm: We put our heads together to solve the ‘Whistle’ challenge and – yes! – we were the third ones to solve it. Our first big win: 90 points!

01:45 am: last flag for this session. It took us a while to figure out where the flag was hidden since this was a forensics exercise.

Until 4 am we kept searching but we were all too tired to keep on digging for flags so we took a nap to continue with clear heads the next morning.

11:15 am: submitted the new flag! What’s next? The time is ticking guys! The contest would end in only seven hours. We had to come back to this one ‘XYZ-adventures.com Data Exfiltration’ challenge several times. The organisation provided us with data capture files and we had to find where the flag was hidden in that giant pile of data. One team member found credentials that were sent while capturing the data. With these plain text credentials we could log into his mail account and retrieve a word document from his mailbox.

12:45 pm: The flag was found in the document properties.

05:15 pm: We submitted the flag we just found but we needed to find some others.

06:00 pm: END of competition, Team BlumBlumShub ranked 24th place on the scoreboard.

During the competition we heard only the first eight would qualify to compete in the finals, afterwards we received a mail that said the top fourtyfive can join a second CTF in two weeks and compete for another eight places in the finals.
So stay tuned for more in a few weeks!