Cyber SEA Game 2023 | Recap

2023-11-10

CTF

This post is a recap of my team’s journey participating in the Cyber SEA Game 2023 in Bangkok, Thailand (November 9-10, 2023).

Results of the ASEAN Student Contest on Information Security 2023

The RobinHust team from Hanoi University of Science and Technology was deeply honored to lead Phase 1 of the ASEAN Student Cybersecurity Contest 2023. Thanks to this achievement, the team was selected to represent Vietnam at the Cyber SEA Game 2023 in Bangkok, Thailand.

This was an incredible opportunity for RobinHust to learn, network with strong teams in the region, and compete on an international stage.

Cyber SEA Game 2023 (Bangkok - Thailand)

Before the competition, I asked a friend from the Philippines team to take a photo for our team :V, and this picture was later spammed in every news article mentioning RobinHust…

:3 I don’t really want to comment on this card, but it seemed quite difficult to keep in good condition.

Overview of the Vietnamese Team’s Performance

In the first 5 minutes, when the Vietnam team received the server and accounts, and performed operations like changing passwords and checking everything, we were surprised to see that 6 other teams had already submitted challenges one after another, though it wasn’t clear what had happened.

The team members managed their workload clearly, though it was a pity that Huy and Thành, who specialize in Binary and Web Exploitation, didn’t get any challenges related to their strengths. Specifically:

Viet Anh handled Cryptography and Network
Hoang Huy took on Hacking Challenge 1
Thai Son tackled tasks in OSINT, Steganography, Forensic, Reversing, and Memory
Chi Thanh was responsible for Hacking Challenge 2.

We felt the pressure as the Singapore team worked quickly and finished in a short time and they even rang the bell after each challenge done 💢💢. However, RobinHust didn’t lose heart and gave our all to complete our challenges. Notably, the challenges didn’t just require basic attack techniques but also creativity and “gut feeling” (or as we call it, bruteforce :3):

In the Flag #03: Cracking a Zip File challenge under the Cryptography category, there was a requirement to decode the password openthesamesenovemberXXXX. Bruteforcing the last 4 characters could take some time (according to the official solution from the organizers). However, through logical reasoning, we successfully tested the last 4 characters as 2023, making the process quick and easy (wtf???).
Hoang Huy successfully conquered Hacking Challenge 1, overcoming challenges one after another. The Vietnam team showcased excellent skills in solving this challenge by carefully reading the organizers’ documentation and testing beforehand.
Thai Son successfully handled challenges in Steganography, Memory, Reversing, and unlocked the Digital Forensics challenges.
Chi Thanh assist Thai Son and Viet Anh with Digital Forensics and Cryptography challenges before returning to support Hoang Huy on Hacking Challenge 2.
Everything went smoothly, and the team completed all the challenges in 3 hours and 30 minutes (Although the duration of the contest is 24 hours, wtf part 2???).
During the competition, most teams had a high rate of incorrect submissions and wasted a lot of time guessing in the Flag #03 Initial execution challenge under the Forensic category, which provided a long list of fake flags that we had to test to solve.

Phase 1: The Start of the Competition (About 1 Hour After the Start)

Our team didn’t have a smooth start, becoming the slowest among the 10 teams to solve the first challenge.

Other teams began submitting challenges from 12:00, and it wasn’t until 12:22 that the Vietnam team submitted Viet Anh’s first challenge. (I’m genuinely impressed by how calm the team members stayed despite this.)

After that, the members gradually submitted the first challenges of each category (though we were still at the bottom of the leaderboard since other teams had already submitted many challenges earlier).

Phase 2: Mid-Game (About 2 Hours After the Start)

After getting stuck on the initial challenges, our team regained momentum and successfully tackled the next challenges quickly.

Breakthrough 1: About 30 minutes after solving the first challenge, the team surged from the bottom of the leaderboard to 6th place, trailing behind Singapore, Malaysia, Thailand, Brunei, and Myanmar.

After over an hour into the competition, the Singapore team impressed everyone by completing all the challenges (wtf part 3), ringing the bell each time they “cleared” a category. At that moment, our team felt a bit “shocked,” but we quickly regained composure and pushed through the challenges.

Breakthrough 2: Around 1 hour 45 minutes to 2 hours after the competition began, our team continuously solved challenges in Cryptography, Hacking Challenge 1, and Digital Forensics. This allowed us to surpass the Thailand team and secure a spot in the top 3, just behind Singapore and Malaysia.

Phase 3: End game

Breakthrough 3: After a long struggle with the Digital Forensics and Hacking Challenge 2 due to their guessing nature, with the team’s innate brute force talent, we finally overcame the obstacles and solved all the Digital Forensics challenges. (At this point, Thai Son had practically memorized the source code of all 7 Digital Forensics challenges after being stuck there for so long 🤣)

We finalized the with Vietnam’s final submission for Hacking Challenge 2 by Hoang Huy. This pushed us ahead of Malaysia, making us the second team to complete all challenges after nearly 4 hours.

P.S.: About an hour later, the third team, Team Thailand, also completed all the challenges, allowing the organizers to determine the top 3 teams for the Cyber SEA Game awards: First, Second, and Third.

Leaderboard

Award Ceremony

Although there are some regrets about missing the Cyber SEA Game championship title and the ticket to participate in SECCON in Japan, RobinHust has gained invaluable insights—highlighting the important role of meticulous preparation before a competition and the ability to stay calm when unexpected challenges arise.

This achievement marks a pivotal milestone for both our team and Hanoi University of Science and Technology. We embrace it as a valuable learning experience and a driving force to push ourselves further in the future.

And here’s something special—our official certificate: