Step 190. Finding/Forming a Team + the CTFtime Calendar — Turning a Solo Game into a Team Sport

Level 3 — CTF in the Field & Advanced Attack Skills | Difficulty ★★☆☆☆ | Estimated time: 2 hours

Prerequisites: you’ve experienced the CTF tasters of Steps 176–180 (five categories), and you’ve picked your main category in Step 181.

What you need: a web browser, a notes app or spreadsheet, (optional) a CTFtime account and a Discord account.
⚠️ All exercises in this chapter are for your own lab and legal platforms only. Applying them to unauthorized systems is a crime. CTFtime and the various CTF competitions are legal platforms opened for participation.
Caution: this chapter is about environment design, not a new attack technique, so there are no local measurements. CTFtime screens and competition lists are marked as "Screen example," and you must verify actual schedules and rules yourself.

Up to here, you’ve solved alone. But CTF’s main stage — the international competitions held every weekend — is a team game. One person can’t be good at Web, Pwn, Reversing, Crypto, and Forensics all at once. Only when specialists by category gather does the top tier come into view, and above all, the speed of learning together is different. Today we finish three things: how to read CTFtime, the hub of worldwide competition schedules; how to find or build a team that fits you; and a preparation checklist for your first competition.

1. Learning Objectives

By the end of this chapter, you will be able to:

Read CTFtime’s competition calendar, team pages, and ranking structure
Interpret difficulty, format (Jeopardy, etc.), and timing on a competition page to pick your first competition
Explain the principle of a team composition that doesn’t overlap your main category
Draft team rules (communication, solution sharing, Write-up division)
Explain a path to compete solo and network even without a team

2. Background Knowledge — Today’s Tools and Concepts

Today’s Tools at a Glance

Category	Details
Language/environment	Web browser (CTFtime.org), spreadsheet (competition schedule), Discord/communities (finding teammates)
Today’s screens/documents	CTFtime calendar, competition pages, team pages; team rules draft; first-competition prep checklist
Concepts needed	Jeopardy vs. Attack-Defense, competition weight and ranking points, category division
Today’s deliverable	A 3-month competition schedule + a team confirmation (or participation plan) document

2-1. Why CTF Is a Team Sport

A single CTF competition puts out dozens of problems. Covering five categories alone over 48 hours is close to physically impossible. So teams are designed for category coverage — something like "1 Web, 1 Pwn, 1 Crypto, 1 all-rounder."

A team’s benefit isn’t only points. The time after a competition ends when teammates explain their solutions to each other — the Write-up review — is the core of team learning. Solo, a problem you don’t know stays forever unknown; on a team, someone else’s solution becomes your skill.

What’s the right team size? For a beginner team, 3–5 people is the practical form. With 2, category gaps are large; past 6, communication costs during a competition spike and nothing rolls without a progress board. The standard path is to start small and elite, run two or three competitions together to check the chemistry, then grow.

2-1a. "I’m Not Good Enough — May I Join a Team?" — The Most Common Hesitation

Many beginners freeze at this point. The answer is settled: yes, you may. The CTF community is generous with newcomers’ questions, and from a team’s perspective, "a newcomer who picks the right problems to work on" is an asset. What you’ve built following this book this far — tasters in five categories and a main category — is already more than application qualifications. It’s not grounds for hesitation; it’s grounds for applying.

2-2. CTFtime — The Hub of Schedules and Rankings

CTFtime (ctftime.org) is a hub site collecting worldwide CTF competition calendars, team registrations, results, and rankings. It does three jobs.

Calendar: the list of upcoming competitions. Most run on weekends (Fri–Sun, in UTC). Time-zone conversion is essential — a UTC Friday-evening start is commonly early Saturday morning in Korea.
Competition pages: format, restrictions (student division or not), weight, and links to past problems and Write-ups. Look here when picking your first competition.
Team pages and rankings: once you make a team, competition results accumulate and world/country rankings are assigned. Each competition has a different weight, so bigger competitions (like DEF CON qualifiers) carry bigger ranking points.

2-3. Two Competition Formats

Jeopardy: the format you’ve been doing so far. Problems by category are listed with point values, and solving earns points. Consider every beginner competition to be this format.
Attack-Defense: each team receives an identical vulnerable server, and you attack others’ servers while defending your own. The format of advanced competitions — for now, just know "this exists."

When a competition page says "Quals (qualifiers)," it’s the gateway of a big competition with a separate final. Qualifiers are mostly online Jeopardy, so beginners can enter, but the problem level lives up to the name. Too heavy for a first competition — suitable as a challenge goal for your second or third.

2-4. The Principle of Finding Teammates — People Who Don’t Overlap

The first principle when picking teammates: find people who don’t overlap your main category. Two Web specialists together solve Web fast, but the Pwn problems never open. Your main category, chosen in Step 181, becomes the standard of team design here.

Where to look: school security clubs, teammate-recruitment posts on domestic security communities like Dreamhack, Discord security servers, and — the highest success rate — competition chat rooms themselves. Very often, people who entered solo become a team by agreeing to do the next competition together.

2-5. Roles Inside a Team — An Axis Different from Categories

Apart from category distribution, a team also has an axis of roles. The bigger the competition, the more these roles decide the score.

Captain: coordinates problem assignment and makes the cut-loss call — "this problem stops here." In a 48-hour competition, the scarcest resource is not problems but teammates’ time.
Infrastructure lead: prepares the Discord server, shared folders, progress board, and common tooling before the competition.
Recorder (can double up): memos solution processes as they happen. Once the competition ends, memory evaporates fast — only memos become Write-ups.

For a beginner team, even just deciding "who does the recording" makes a big difference, short of perfect role division.

3. Follow Along

3-1. Touring CTFtime (Screen example)

In your browser, go to ctftime.org and sign up. The top menu is structured roughly like this (Screen example — the actual layout may change):

[CTFtime logo]   Calendar | Events | Teams | Rankings | Write-ups

Enter Calendar and upcoming competitions appear in time order. Each entry looks roughly like this (Screen example):

Example CTF 2026
  Fri, 10 Apr. 2026, 12:00 UTC — Sun, 12 Apr. 2026, 12:00 UTC
  Format: Jeopardy   Weight: 24.70   Official URL: ...

How to read it: ① start/end are UTC — convert to Korea time (+9). The example above starts Saturday 9 PM KST. ② Confirm it’s Format: Jeopardy. ③ The higher the Weight, the bigger the competition where strong teams flock — for a first competition, a new or junior competition with low weight is best.

3-2. Building a 3-Month Competition Schedule

Make a table in a spreadsheet. Set up the columns like this.

Competition	Start (Korea time)	End	Format	Weight	Joining?
(example) Example CTF	4/10 (Fri) 21:00	4/12 (Sun) 21:00	Jeopardy	24.70	Considering

After filling in three months’ worth, fix one of them as your "first competition." Criteria: ① can you fully free up the weekend, ② is it Jeopardy, ③ is there a beginner-friendly label among "Beginner," "Junior," "Quals"?

That competitions run every weekend is no accident — it’s the only time slot when workers and students worldwide can run simultaneously. Your schedule sits under the same constraint. Not "when does it run" but "can I clear that weekend" is the real selection criterion.

3-3. Finding or Forming a Team

Two roads.

Road A — Join an existing team: apply to community recruitment posts. In your application message, write ① your main category (Step 181), ② the number of problems you’ve solved or platforms so far, ③ the time you can spend on competitions. One concrete line like "new but solved 30 Web problems and can give 20 weekend hours" beats ten lines of passion.

Road B — Form your own: gather 2–4 like-minded people. Four things to decide.

Team name — the name to register on CTFtime. Hard to change, so choose carefully.
Category distribution — list teammates’ main categories and confirm at least 3 categories are covered.
Contact channel — creating a Discord server is standard. Voice channels are essential for real-time collaboration during competitions.
CTFtime team registration — create the team page and invite teammates.

3-4. Drafting Team Rules

Decide these before the competition and you won’t fight. Four items minimum.

[Our Team Rules Draft]
1. Communication: stay on Discord during competitions. Share problem pickups/drops in the channel immediately.
2. Solution sharing: briefly share grabbed problems and progress every 30 minutes.
   (prevents the waste of two people unknowingly holding the same problem)
3. Progress board: manage per-problem assignee/progress/solved status in a shared spreadsheet.
4. Write-ups: within one week after the competition ends, solvers write and non-solvers review.

3-5. If You’re Solo — That’s Normal Too

It’s fine if a team doesn’t materialize right away. Enter solo → talk with people in the same situation in the competition chat room → team up for the next competition is a common path. Tips for entering solo: ① score on the easy problems you can solve first, ② join solution discussions in the competition Discord, ③ share your Write-up when it ends. One Write-up is a business card that draws "let’s work together" offers.

3-6. First-Competition Day Checklist

On the day of your confirmed first competition, run this list before the start.

[1 hour before the competition]
- [ ] Re-confirmed start/end times in Korea time
- [ ] Competition platform account login and team registration done
- [ ] Discord voice/text channels open
- [ ] Ready to move the problem list onto the progress-board spreadsheet
- [ ] Meal/sleep plan decided (in a 48-hour competition, strategic sleep is a skill)

[Right after the start]
- [ ] Skimmed the whole problem list and assigned owners by category
- [ ] Opened the scoreboard by starting with easy problems (ones many participants solved)

The last item matters. "Easy problems first" right after the start is not pride but strategy — early points build team morale, and morale becomes the stamina that cracks the hard problems late.

4. Missions & Exercises

Mission — Confirm Team and Calendar

Sign up for CTFtime and organize at least 5 competitions over the next 3 months into the 3-2 table.
Fix one as your first competition and write your reasons in three lines (format/difficulty/time grounds).
Execute either Road A (apply to join) or Road B (form your own). If neither is feasible, write a "solo entry + chat-room networking" plan.
If you have a team (or plan to make one), adapt 3-4’s rules draft into your team’s version and save it.
Register the 3-6 day-of checklist in your calendar app matched to the confirmed first competition’s date, with a 1-hour-before-start alarm.

Exercises

Exercise 1. Name four pieces of information to look at on a CTFtime competition page when picking a first competition.

Exercise 2. Explain the reason for the principle "recruit people who don’t overlap your main category," from the category-coverage perspective.

Exercise 3. Compare Jeopardy and Attack-Defense from the perspective of "what do you do."

Exercise 4. Find two devices in 3-4’s rules that prevent the waste of "two people unknowingly holding the same problem" during a competition.

5. Model Answers & Completion Criteria

Mission Model Answer

How to verify: ① does the schedule have at least 5 competitions with start times converted to Korea time (writing UTC as-is loses points — the accident of mistaking a dawn competition for an afternoon one actually happens)? ② Do the first-competition reasons include "Jeopardy," "beginner-friendly/low weight," and "time secured"? ③ Does a team confirmation document or solo-entry plan exist? ④ Does the rules draft have all four items: communication, sharing, progress board, Write-ups? ⑤ Is the day-of checklist actually registered in a calendar with an alarm?

Exercise Answers

Answer 1. ① format (is it Jeopardy), ② start/end times (UTC — Korea-time conversion needed), ③ weight (lower is better for beginners), ④ participation restrictions (student division, regional limits). Additionally checking whether past Write-ups exist helps you gauge difficulty.

Answer 2. Competition scores come from how widely you cover problems across categories. With two specialists in the same category, that category’s processing speed rises, but the other categories’ problems stay unopened by anyone. Only when categories don’t overlap does the whole team’s coverage widen.

Answer 3. Jeopardy is a format where you solve problems prepared by the organizers for points — the attack target is only the problem servers. Attack-Defense is a format where each team operates its own server, attacking other teams’ servers while patching its own vulnerabilities to defend. If the former is problem-solving, the latter is a real-game accompanied by operations.

Answer 4. ① "Share pickups/drops in the channel immediately" — who holds what is visible in real time. ② "Shared spreadsheet progress board" — look at the per-problem assignee column and duplicate pickups are blocked at the source.

Completion Criteria Checklist

[ ] I can say what CTFtime’s calendar, competition pages, and team pages each show
[ ] I converted UTC notation to Korea time and built a schedule
[ ] I can explain the first-competition selection criteria (format, difficulty, time)
[ ] I can explain the "non-overlapping categories" principle when picking teammates
[ ] I can name the four team-rule items (communication, sharing, progress board, Write-ups)
[ ] I have a team confirmation, or a solo-entry + networking plan, as a document
[ ] My first competition’s day-of checklist is registered in a calendar

6. Common Pitfalls & Fixes

Wall 1. I mistook the competition start time and missed it

Symptom: "starts Friday evening," they said, but you open it and half a day has already passed.

Cause: CTFtime displays in UTC. Korea is UTC+9, so a UTC Friday 12:00 start is Friday 9 PM Korea time. Conversely, a UTC Sunday end can become early Monday morning in Korea.

Fix: write the schedule’s time column in Korea time from the start, and register the converted time in your calendar app too.

Wall 2. No reply to my team application message

Cause #1: an "I’ll work hard"-type message — from the team’s side, it contains zero information. #2: your category overlaps that team’s composition.

Fix: include these three numbers — ① main category, ② problems solved or platform record, ③ available hours. And first check whether the "categories sought" in the recruitment post matches yours.

Wall 3. I couldn’t solve a single problem in my first competition

Cause: you most likely picked a big, high-weight competition for your first. In those, even the easy problems are hard by beginner standards.

Fix: it’s not failure but measurement — record "in which category, at which problem type did I get stuck?" Pick the next competition from ones labeled "Beginner/Junior," and fill the stuck types not through competitions but through track study from Step 191 onward.

Wall 4. We made a team but everyone plays separately during competitions

Symptom: nobody knows who’s looking at which problem, and at the end it turns out three people looked at the same one.

Cause: you started without rules.

Fix: agree before the competition — even 3-4’s rules draft as-is is fine. Especially keeping just the two — "share on pickup" and "progress board" — visibly changes a team’s efficiency.

Wall 5. I can’t find a team

Cause: you’re treating finding teammates as "a task to complete before competing."

Fix: flip the order — entering a competition solo is part of finding teammates. Competition chat rooms always have people who came alone, and offers come to those who share Write-ups. The only real loss is postponing competitions because you have no team.

Wall 6. In a 48-hour competition, the whole team burned out in the second half

Cause: everyone ran at full throttle on start-day excitement and collapsed simultaneously on day two. CTF is not a sprint; it’s a two-day match.

Fix: set a shift sleep plan before the competition — the late-game results differ between teams that decided "who sleeps when" and teams that didn’t. The captain’s role (2-5) is exactly this resource allocation. For a first competition, starting with a short 24-hour one is also a method.

7. Summary

Today’s Concepts

Concept	One-line explanation
CTFtime	The hub of worldwide CTF schedules, teams, and rankings
Weight	A value showing a competition’s scale/level — higher means stronger teams gather and bigger ranking points
Jeopardy	A format of solving problems by category for points — the standard for beginner competitions
Attack-Defense	An advanced format of defending your server while attacking others’
Category coverage	The breadth of categories a team can handle — the first principle of team design
Role division	Captain (cut-loss calls), infrastructure, recording — a team’s second axis, separate from categories
Write-up review	Post-competition time explaining each other’s solutions — the core of team learning
Progress board	A shared table of per-problem assignee/progress/solved status — the duplicate-pickup prevention device

Today’s Tools and Documents

Tool/document	What it does
CTFtime Calendar	Explore upcoming competitions (mind the UTC notation)
CTFtime competition page	Check format, weight, restrictions, past Write-ups
Competition schedule (spreadsheet)	3-month calendar + first-competition confirmation
Team rules draft	Agreement on communication, sharing, progress board, Write-up division
Competition Discord chat room	The front line of teammate-finding for solo entrants
Day-of checklist	Pre-start check of time, accounts, channels, progress board, sleep plan

Community Etiquette — Remember Just One Thing

Whether finding a team or in a competition chat room, first impressions are made by question quality. Not "it doesn’t work" but "I got this far, and I’m stuck at this point" — answers gather to people who show what they tried first. Same when reading Write-ups: a line of thanks and a question, rather than just taking, is the seed of the next collaboration.

One warning to add. CTFtime rankings are addictive. Rankings are a means, not an end — a team that skips solution study to climb ranks stalls fast. Teams that ask "what did we newly learn?" every time a competition ends last long.

An Instinct More Important Than Commands

Sitting between technical chapters, today looks like a rest day, but from a career perspective it may be the highest-yield day. More than solving 100 problems alone, running one competition as a team and exchanging Write-ups is faster in both skill and connections. Signing up for CTFtime and building a schedule takes one hour — and that one hour changes the structure of your next year of learning.

Once every box is checked, Step 190 is complete. Click the checkbox in the sidebar to save your progress.