$ ctf -h
Grey Cat The Flag is an annual CTF hosted jointly by NUS Greyhats and Division Zero (Div0), supported by the National Cybersecurity R&D Lab.
Remember to stay tuned to our socials and join the GreyCTF Discord to stay updated!
What is CTF?
CTF (Capture The Flag) is a kind of information security competition that challenges you to solve a variety of tasks ranging from a scavenger hunt on wikipedia to basic programming exercises, to hacking your way into a server to steal data. In these challenges, the contestant is usually asked to find a specific piece of text that may be hidden on the server or behind a webpage. This goal is called the flag, hence the name!
If you are new, don’t worry! We will be sharing resources in our Discord server every now and then.
$ stat ctf
There will be two categories this year: Local and International. All participants (regardless of category) must be undergraduate or pre-university students, such as NSFs, JC, Poly, or ITE students.
Local Category: Teams must consist entirely of Singapore Citizens or Permanent Residents.
International Category: Teams that do not qualify for the Local Category will compete in the International Category.
The top 10 Local teams and top 10 International teams will qualify for the onsite finals. Each team may send up to 4 members to attend the onsite finals.
$ stat summit
We are excited to announce that we are hosting our very own Summit this year in Singapore!
This event will include talks and workshops on cybersecurity, with plenty of chances to meet new people during breaks and over lunch and tea.
Plus, you will have the opportunity to hear from our sponsors as well as concluding with the CTF prize presentation.
Registration and additional information for the summit can be found here!
$ where ctf
| dates | events |
|---|---|
| 30th May, 10am to 31st May, 10am | Qualifiers, Online |
| 27th June, 10am to 28th June, 10am | Finals @ NUS COM1 |
| 4th July, 9.30am to 4th July, 5pm | GCTF Summit @ NUS COM1 |
(all timing are in GMT+8 timezone)
$ man prize
Coming soon! Watch this space.
$ whois sponsors
We would like to extend our heartfelt gratitude to our sponsors.
Gold Sponsor
Silver Sponsor
Infra Sponsor
$ FAQ
Join our Discord server if you have more questions.
Q: Is there a team size limit for qualifiers?
A: There is no team size limit for qualifiers. You can have as many team members as you want. However, please note that each team can only send up to 4 members for the finals.
Q: What categories are there?
A: Web, Pwn, RE, Blockchain, Forensics, Misc
Q: Is this CTF beginner friendly?
A: Yes! But we also have hard challenges for the stronger teams.
Q: What's the flag format?
A: grey{...}
$ history
Past Winners
2025
| ranking | prize |
|---|---|
| 1st place | slight_smile |
| 2nd place | HotpotHunchos |
| 3rd place | mallows |
2024
| ranking | prize |
|---|---|
| 1st place | slight_smile |
| 2nd place | nsmallows |
| 3rd place | 粥 |
2023
| ranking | team |
|---|---|
| 1st place | r3kapig |
| 2nd place | DiceGang |
| 3rd place | Social Engineering Experts |
2022
| ranking | team |
|---|---|
| 1st place | catssg |
| 2nd place | nushmellows |
| 3rd place | Stranglehold |