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!

Join Anytime

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

Not a Competition

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

Solution Sharing Rules

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

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Today's Challenge

Submissions (latest 3)

serioton

SOLVED!

Sep 21, 3:19 PM

sikoderu

SOLVED!

Sep 21, 3:17 PM

syn9

SOLVED!

Sep 21, 3:12 PM

Leaderboard

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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.

Upcoming challenges reveal the , , and in advance.

Sep 2026

Solved

Unsolved

Upcoming

Mon

Tue

Wed

Thu

Fri

Sat

Sun

tchen

Springing

Web

Medium

74 solves

admin

QUIZ ALPACASHOCK

Misc

Welcome🌱

124 solves

hiikunz

base 16-32-64

Misc

Easy🌱

101 solves

3-4

tan90909090

Let's Shut Down Linux

Misc

Medium

63 solves

baumroll1234

Vending Machine: Revised Version

Misc

Easy🌱

87 solves

6-8

minaminao

Bitflip RSA

Crypto

Hard

56 solves

minaminao

Bitflip RSA

Crypto

Hard

56 solves

9-11

minaminao

＼^o^／

Misc

Hard

43 solves

12-13

tan90909090

sin function vs. fsin instruction

Rev

Misc

Medium

55 solves

14-15

tan90909090

integer division

Misc

Medium

69 solves

16-18

edwowmath

neighboRhood_diStAnce

Crypto

Hard

40 solves

19-21

hiikunz

nested eval

Misc

Hard

39 solves

hiikunz

nested eval

Misc

Hard

39 solves

22-24

2501

The 3rd

Crypto

Hard

4 solves

Coming soon

Want a harder challenge?

Go to B-SIDE

Writeups

Writeup for nested eval

shiragi

nested eval

23 minutes ago

Writeup for Alpaca Bank

gattoartz

Alpaca Bank

4 hours ago

Writeup for Read Assembly

gattoartz

Read Assembly

5 hours ago

Writeup for hit-and-miss

gattoartz

hit-and-miss

5 hours ago

Writeup for simpleoverflow

gattoartz

simpleoverflow

5 hours ago

Writeup for neighboRhood_diStAnce

baumroll1234

neighboRhood_diStAnce

2026/09/18 22:37

Writeup for integer division

lumma

integer division

2026/09/16 04:25

Writeup for integer division

baumroll1234

integer division

2026/09/15 21:16

Writeup for what-is-my-pointer

fms

what-is-my-pointer

2026/09/15 13:55

Writeup for simple ROP(アセンブリ解説多め)

curetwinkle

simple ROP

2026/09/15 03:55

Rows:

Alpaca Bank

Topic: GeneralReleased: Dec 11, 2025

423 solves

Web

Medium2.0

hiikunz