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Daily AlpacaHack

A daily CTF challenge with a fun new puzzle every day

What is Daily AlpacaHack?

We publish one simple, beginner-friendly or educational CTF challenge every day!

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Solve within 24 hours of release to appear on the leaderboard.

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Discussion with friends or AI is welcome (account sharing is prohibited).

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Today's Challenge
rsk0315
Bounds Checking
Pwn
Hard
16 solves
Submissions (latest 3)
cyanos

SOLVED!

May 9, 6:15 PM

tadanobutubutu

SOLVED!

May 9, 5:32 PM

Leaderboard

Try the first challenge

Is this your first CTF? Let's begin by tackling the first challenge released on Daily AlpacaHack.

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admin
AlpacaHack 2100
Misc
Welcome
1,760 solves
Upcoming challenges reveal the , , and in advance.
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Writeups

tadanobutubutu

Writeup for reused n

tadanobutubutu

ja
reused n

1 hour ago

kakur41

Writeup for Daily AlpacaHack 5/3-5/9

ja
reused n

+6

3 hours ago

Writeup for Vending Machine

author
ja

5 hours ago

tadanobutubutu

Writeup for Vending Machine

Daily AlpacaHackに挑戦するつくよみちゃん 05/08 misc/Vending Machine/baumroll1234

Daily AlpacaHackに挑戦するつくよみちゃん 05/07 misc/Permission Denied 3/minaminao

Rows:

Log Viewer

Topic: Remote Code ExecutionReleased: Dec 22, 2025

232 solves
Web
Medium

by

tchen

tchen

Simple log viewer with regex feature.

Beginner Hint: What is an instance spawner?
  • In CTFs, some challenges require dynamically creating a separate challenge server for each player (or team).
  • For example, if a player can change the state of a challenge server, it may affect other players.
  • To handle such issues, an instance spawner is provided.
  • On AlpacaHack, clicking the "Spawn Challenge Server" button automatically creates an isolated challenge server for each user.
  • This challenge also uses an instance spawner.
  • To help reduce server load, please try to solve the challenge locally before spawning.
  • Note that on Daily AlpacaHack, even for challenges that do not require an instance spawner, the challenge server may be stopped after some time has passed since release, and the "Spawn Challenge Server" button will then appear.
Beginner Hint: The Starting Point of the Attack
  • The goal of this challenge is to read the flag file located in the root directory.
  • The starting point for achieving this is an OS command injection in the query part of the awk command.
Beginner Hint: Pitfalls in Payload Construction
  • In Python, subprocess.run method executes commands without going through a shell like Bash.
  • As a result, you cannot split commands using ; or perform command substitution with $(command).
log-viewer.tar.gz
descriptionsolveswriteups