$ ctf -h

Grey Cat The Flag is an annual CTF hosted by NUS Greyhats.

Registration is now open on CTFd!

Remember to stay tuned to our socials 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.

Learn more about CTFs

$ stat ctf

There will be two categories this year

  1. Local Category consists of: NSFs, students that are currently enrolled in an educational institute in Singapore (team should consist of at least one Singapore Citizen)

  2. Open Category consists of: all participants who do not qualify for the local category, participants who are eligible for the local category but opts in for the open category

There will be an onsite finals for the top 20 teams in the local category. Each team may send up to 4 people for the onsite finals.

Regrettably, we are unable to accommodate international teams for the onsite finals this year.

On the bright side, we will have attractive cash prizes up for grabs the top 3 teams in our Grey Cat The Flag Open category.

$ 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.

We hope that you will join us for this fantastic summit!

The summit will happen on 10th August, from 1000h to 1630h (SGT) at NUS COM1 Level 2.

1000h - 1015hDSTA Talk
1015h - 1030hDSO Talk
1030h - 1045hISD (MHA) Talk
1045h - 1100hPrize Presentation
1100h - 1130hTalk 1 - ?
1130h - 1200hTalk 2 - ?
1200h - 1330hLunch & Networking
1330h - 1400hTalk 3 - ?
1400h - 1600hWorkshop - ?
1600h - 1630hClosing Ceremony

Concurrently, we will have some booths and activities happening in parallel with the talks that includes (but is not limited to):

  • Hardware Hacking
  • Lock Picking
  • many more…

$ where ctf

20th April, 12pm (GMT+8) to
21st April, 12pm (GMT+8)
Qualifiers, Online
27th July, 10am (GMT+8) to
28th July, 10am (GMT+8)
Finals @ NUS COM1
10th August, 10am (GMT+8) to
10th August, 4.30pm (GMT+8)
GCTF Summit @ NUS COM1

$ man prize

open category

1st placeSGD 2000
2nd placeSGD 1000
3rd placeSGD 400

local category

1st placeSGD 4000
2nd placeSGD 2000
3rd placeSGD 1000
4th-10th placeSGD 400
special prizesstay tuned!

$ whois sponsors

We would like to extend our heartfelt gratitude to our sponsors .


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, Crypto, RE, Blockchain, 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


1st placer3kapig
2nd placeDiceGang
3rd placeSocial Engineering Experts


1st placecatssg
2nd placenushmellows
3rd placeStranglehold

Past Sponsors

Bakkhos Labs
Ensign InfoSecurity
NUS Computing