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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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Today's Challenge

Submissions (latest 3)

SOLVED!

Sep 22, 3:03 PM

SOLVED!

Sep 22, 2:14 PM

SOLVED!

Sep 22, 1:23 PM

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

AlpacaHack 2100

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Sep 2026

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tchen

Web

Medium

74 solves

1

admin

QUIZ ALPACASHOCK

Misc

Welcome🌱

126 solves

2

hiikunz

Misc

Easy🌱

102 solves

3-4

tan90909090

Let's Shut Down Linux

Misc

Medium

63 solves

5

baumroll1234

Vending Machine: Revised Version

Misc

Easy🌱

88 solves

6-8

minaminao

Crypto

Hard

56 solves

　

minaminao

Crypto

Hard

56 solves

9-11

minaminao

Misc

Hard

43 solves

12-13

tan90909090

sin function vs. fsin instruction

Rev

Misc

Medium

55 solves

14-15

tan90909090

integer division

Misc

Medium

70 solves

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edwowmath

neighboRhood_diStAnce

Crypto

Hard

41 solves

19-21

hiikunz

Misc

Hard

43 solves

　

hiikunz

Misc

Hard

43 solves

22-24

2501

Crypto

Hard

25 solves

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Want a harder challenge?

Writeups

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Writeup for Vending Machine

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2026/09/21 18:28

Writeup for Flag Printer 2026

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2026/09/21 18:28

Rows:

Let's Shut Down Linux

Topic: System CallReleased: Sep 3, 2026

63 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