Thndr Security CTF

Read this page in full before you begin.

What this is

There are five hidden flags in an environment provisioned just for you. Each flag is a signed JWT — copy the full token string and paste it into your final report.

The flags increase in difficulty and tell one continuous story. You're not expected to find all five — a partial result with a thoughtful writeup is a strong submission.

Time limit

36 hours from the moment your environment was provisioned (this is the timestamp on the invite email you received). The flag tokens expire at that instant — late submissions verify as expired and won't count.

The 36 hours are wall-clock, not active time. Sleep, eat, take breaks. Burnout is not the test.

What to submit

  1. The flag JWT strings you obtained (one per line, prefixed f1= through f5=).
  2. A short written report (markdown, ~1–3 pages) covering, per flag:
    • How you discovered the path
    • What dead-ends or wrong turns you took
    • If you were defending this environment, what would you fix?

The report carries equal weight to the flags. A clean writeup with three flags beats five flags with no explanation.

Rules

DO these are encouraged

  • Use the public internet, documentation, search engines, and AI tools (ChatGPT, Claude, Copilot) however you like.
  • Read code, read configs, enumerate endpoints, explore the environment by hand.
  • Take notes as you go — you'll need them for the report.

DON'T these are out of scope

  • Don't attack other candidates' environments. Multiple candidates are active at the same time.
  • Don't attack Cloudflare, the reverse proxy, the underlying infrastructure, or the host machines — only the lab targets are in scope.
  • Don't run automated vulnerability scanners or automated exploitation frameworks (Burp Pro active scan, sqlmap, nuclei, metasploit auto-pwn, etc.). Manual use of utilities is fine.
  • No kernel-level exploits. The intended paths don't require them.
  • Don't denial-of-service the environment (no fork bombs, no resource exhaustion). You have a quota; respect it.
  • Don't share the flag JWTs or your solution with other candidates. Tokens are per-candidate-signed; sharing is detectable.
  • Don't submit anyone else's work as your own.

What we observe

Everything you do inside the lab is logged. The panel reviews your activity as part of grading the report — so be honest about what you actually did.

Your environment

Begin challenge →

Questions or environment resets: [email protected] · CTF v1 · Good luck.