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July 31, 2025 | by siunam | Tags: CTF, Finals, Travel, Korea

2025 Hacktheon Sejong Finals and Seoul Trip

Table of Contents

HACKTHEON SEJONG 2025 Preliminaries

Back in April, me and my university CTF team, NuttyShell, participated in HACKTHEON SEJONG 2025 Preliminaries (2025 HackTheon Sejong International Collegiate Cyber Security Competition) in the "Beginner B" category. Ultimately, we ranked 5th place and qualified for the finals, which is held in South Korea, Sejong city. Here's the preliminary scoreboard and qualified teams:

Overall, this 9-hour preliminary's quality is average. Not too good, not too bad.

HACKTHEON SEJONG 2025 Finals

Before Finals

On July 9th morning, we boarded to the Cathay Pacific's CX410, departing from Hong Kong International Airport (HKG) to Incheon International Airport (ICN):

(Look at that majestic Boeing 777-300ER!)

Oh btw, this is my first time traveling outside of Hong Kong! I felt really exciting! I even filmed a takeoff video to memorize this moment:

After taking off and reaching at the cruising altitude, we are served with our pre-selected lunch. For me, I selected the "Low Calorie Meal Lunch" set, just because I wanted to try what it tastes like:

As expected, it was just some beans, eggs, and fruits. The taste is, in my opinion, okay-ish. Of course, I wasn't expecting it will taste good at all :D

After 3 hours of short flight, we landed on ICN safely!

Although the immigration queue is longer than I expected, we eventually passed the immigration check as well as getting our luggages:

After some time, we headed to a fast food restaurant inside the airport for a small dinner.

One thing that surprised me in Korea is that the government frequently sends emergency notifications (Emergency Alert System), like the following:

Translated by Google Translate:

We are looking for Mr. Hwang Eun-jong (male, 81 years old), who is wandering around Jung-gu. 160cm, 50kg, green short-sleeved shirt, black pants, straw fedora, black shoe.

svo[.]la/zLaVGmn / 182 [Incheon Metropolitan Police Agency]

In Hong Kong, at the time of this blog post, I only received this kind of notification once in 2022, and it's about a hospital is temporarily becoming a designated hospital for COVID-19 patients.

Right after we finished our dinner, we are boarded the CTF organizers' designated bus to travel to our accommodation hotel, Best Western Plus Hotel. Shortly after settling down our luggages in our hotel rooms, our team decided to have another round of dinner with a Hong Kong team, who are also qualified in the finals in the "Advanced" category.

For readers who are interested, it's a Korean fried chicken restaurant, 자담치킨 세종어진점 (Jadam Chicken Sejong Eojin Branch):

Oh btw, if you want to translate Korean to any language that you wish, I highly recommend you use Naver's Papago app. Before I was recommended this translation app by other people, I used DeepL, the results are… Interesting to say the least 😂:

After finishing those delicious fried chickens, we headed back to the hotel and wait for the next day's finals.

Sidenote, I totally forgot that different ads are targeting different region:

I felt so weird because I'm so used to see ads are in English or Chinese. XD

During Finals

After having a terrible sleep, we arrived at the finals' venue at 9:30 KST, Government Sejong Convention Center (SCC), by the organizers' provided buses:

I'm the guy on the rightmost if you haven't seen me in real life :D

Meanwhile, we are getting bombarded by emergency notifications, lol:

Translation:

Here's a fire prevention guide for the heatwave. When using electrical appliances, please follow these guidelines: use the correct outlet for your air conditioner, avoid using the octopus-style outlet, and be careful when charging electric scooters.

[Fire Administration]

Anyway, here's the montage of our team in the finals:

Note: Both category "Beginner A" and "Beginner B" are combined into category "Beginner", where "Beginner A" is Korean nationals only, "Beginner B" is non-Korean nationals.

Sadly, we didn't get into top 3, and ultimately ranked 5th place in the "Beginner" category.

Here's the solves count, our team scoreboard, and the overall scoreboard in category "Beginner B":

If you are interested in the "Advanced" category, this is their scoreboard:

After the CTF ends, we are required to submit a writeup 1 hour later:

Thankfully, our team already finished up most of the writeup during the CTF!

After the writeup submission deadline, we talked to other teams as well, including the 1st rank team in the "Beginner" category, Starburst Kiwawa:

Some of seasoned CTF players might know this team from Taiwan already. If you don't, they are HITCON CTF finalist in 2023.

Overall, the challenges in the finals are quite fun to solve. One thing that I wish is that web challenges should be a little bit harder, given that all of them have are solved by many teams. (At least 8 out of 10 teams in "Beginner B" category solved all of them). I also want web challenges to focus on client-side vulnerabilities, but sadly it's all server-side focused.

After leaving the venue, we went to a Korean grilled meat restaurant near the hotel, Grill de Woowa:

Again, those foods are very good!

When we finished this dinner, we went back to the hotel and prepare for the next day's award ceremony.

Award Ceremony

I still didn't have a good sleep, maybe I don't feel comfortable with the hotel's bed. Not because those beds are bad, it just doesn't feel like I'm really sleeping in my home's bed.

After having a quick breakfast at the hotel for free:

And packing up our luggages, we went back to the finals' venue. In there, the challenge authors shared some challenges' solution, including the only forensic challenge, Ransom: (Our team didn't solved it)

I'm quite surprised that a forensic challenge would use Mimikatz to solve it! But I guess any other tools that do the same thing also works.

After the solutions sharing by the authors, we are met with the prize presentation!

At the last minute of the award ceremony, it has a lucky draw session. Maybe we can get a free PS5?! Well, nope. 😂

Leaving Sejong

After the finals has ended, we are leaving Sejong and going to our booked Airbnb at Hongdae to begin our trip in Seoul!

While we are moving, I found a zero day in Korea!

Anway, we eventually arrived at our Airbnb and settled down.

Thanks for the organizers to organize such amazing CTF!

Seoul Trip

Day 0 - Resting 💤

When we just checked in at the Airbnb, I decided to buy some drinks nearby. What I discovered next is absolutely accidental!

In a 7-11 near the Airbnb, I found this chocolate drink:

Turns out, this Hershey's Chocolate Drink is super popular in Korea and very tasty! If you're traveling to Korea, remember to give it a try! It only cost 1,900 KRW. (Some places are even cheaper)

After this discovery, some of us also went to Tokyo Night Market. We had some beers, French fries, and Takoyaki: (Yes, we're eating Japanese food in Korea 😂)

However, those foods are average-ish.

Day 1 - No Food No Life

Now we are officially started our trip in Korea!

The first stop was Pungcheon Jangeo(eel), a well-known grilled eel restaurant:

Then, our second stop was… Samsung? Since there's a Samsung store near Hongdae, we decided to have a tour in there.

After that quick tour as well as buying some snacks, we then went to Piggy Bank Stone Grill, a Korean BBQ restaurant:

Day 2 - A Trip to North Korea?

Last night, we booked Korean Demilitarized Zone (DMZ) tour on klook. We were able to ride the tour bus (Almost missed it 😂) and arrived at the DMZ:

We also went to the 3rd Infiltration Tunnel, and man, that tunnel is very narrow and long:

After exploring that tunnel, we had a break and brought some ice creams at DMZ JangdanKong Cafe. For me, I tried the "Soybean Ice Cream", and it tastes pretty good!

Eventually, we arrived to our Airbnb and ordered some Papa Johns pizzas, because there's no Papa Johns in Hong Kong, so we wanted to give it a try:

Day 3 - Shopping and N Seoul Tower

After watching the film World War Z on Netflix (Included in the Airbnb package) in our Airbnb, we went to Jin Ok-Hwa Original Chicken Restaurant for lunch:

After this lunch, we went to different shopping mails nearby to buy some souvenirs back to Hong Kong:

We also planned to visit N Seoul Tower to get the view of the entire Seoul capital:

Sadly, it was absolutely pouring on that day:

After visiting the N Seoul Tower, we went to OPPADAK to enjoy our dinner, which is a Korean fried chicken restaurant:

Day 4 - Palace and Final Goodbye

On our last day in this trip, we first went to National Palace Museum of Korea:

And… Oh:

Unfortunately, there was some renovation works going on in the palace :(

Luckily, the museum is not closed, so we decided to visit there:

After that, we went to this restaurant for a quick lunch:

Why a quick lunch? Because we are going to visit Gyeongbokgung palace for around 2 hours:

Then, we immediately head back to the Incheon International Airport to catch our return flight:

Oh btw, this time I selected the normal meal set, no more beans :D

It's a seafood Fusilli Lunghi Bucati and a Häagen-Dazs strawberry ice cream!

The End

That's all of our trip! Thank you for reading this blog post! Overall, 2025 Hacktheon Sejong finals and the Seoul trip was amazing! Hopefully we'll also get qualified for next year's preliminary!

Additional photos and videos can also be seen in my Google Photos album: https://photos.app.goo.gl/H6ymVheEgg4XcfjU7