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Daily AlpacaHack

A CTF challenge series with fun puzzles to enjoy every day

What is Daily AlpacaHack?

We regularly publish simple, beginner-friendly or educational CTF challenges!

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Solve each challenge within its time window to appear on the leaderboard.

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

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Sharing solutions is allowed only after the challenge period has ended.

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Today's Challenge

Submissions (latest 3)

SOLVED!

Sep 11, 12:51 PM

SOLVED!

Sep 11, 12:49 PM

SOLVED!

Sep 11, 12:20 PM

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Try the first challenge

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

AlpacaHack 2100

Upcoming challenges reveal the , , and in advance.

Sep 2026

Solved

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Upcoming

Mon

Tue

Wed

Thu

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tchen

Web

Medium

69 solves

1

admin

QUIZ ALPACASHOCK

Misc

Welcome🌱

109 solves

2

hiikunz

Misc

Easy🌱

87 solves

3-4

tan90909090

Let's Shut Down Linux

Misc

Medium

55 solves

5

baumroll1234

Vending Machine: Revised Version

Misc

Easy🌱

73 solves

6-8

minaminao

Crypto

Hard

47 solves

　

minaminao

Crypto

Hard

47 solves

9-11

minaminao

Misc

Hard

33 solves

12-13

Planned topicx86

Rev

Misc

Medium

14

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15

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Want a harder challenge?

Writeups

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2026/09/07 13:08

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2026/09/07 13:07

Writeup for Vending Machine: Revised Version

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Vending Machine: Revised Version

2026/09/06 15:02

Writeup for Vending Machine: Revised Version (warn: some code reading ahead)

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Vending Machine: Revised Version

2026/09/06 05:59

Writeup for Let's Shut Down Linux (with reading)

nitcelcius

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Let's Shut Down Linux

2026/09/05 05:49

Writeup for Springing

curetwinkle

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2026/09/05 05:10

Writeup for Let's Shut Down Linux

mizore-fuyu

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Let's Shut Down Linux

2026/09/05 02:40

Writeup for Let's Shut Down Linux

baumroll1234

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Let's Shut Down Linux

2026/09/05 00:33

Writeup for Let's Shut Down Linux

lumma

ja

Let's Shut Down Linux

2026/09/04 23:05

Rows:

Let's Shut Down Linux

Topic: System CallReleased: Sep 3, 2026

55 solves

Medium2.5

by

tan90909090

Tags

Let's shut down Linux by specifying 3 arguments to the reboot system call!

Note: During building a docker image using Dockerfile, over 100MB of data will be downloaded and parallel builds will be performed to build a Linux image. Therefore, building the docker image may take several minutes.

lets-shut-down-linux.tar.gz

description solves writeups