Space Snack

Write Up

Task 1 - Roten to the core (20 points)

You find a roten apple next to a piece of paper with 13 circles on and some text. What's the message?

Given :

Vg nccrnef lbh unq jung vg gnxrf gb fbyir gur svefg pyhr
Jryy Qbar fcnpr pnqrg
pgs{Lbh_sbhaq_gur_ebg}
Npprff pbqr cneg 1: QO 

Decoded (ROT13) :

It appears you had what it takes to solve the first clue
Well Done space cadet
ctf{You_found_the_rot}
Access code part 1: DB

Task 2 - The roman space empire (25 points)

You find a page with a roman insignia at the top with some text what could it mean?

Given :

Jhlzhy ulcly dhz clyf nvvk ha opkpun tlzzhnlz.
jam{Aol_vul_aybl_zhshk}
jvkl whya: NW

Decoded (Caesar Cipher, rotation=7) :

Caesar never was very good at hiding messages.
ctf{The_one_true_salad}
code part: GP

NOTE : Caesar the 1st roman empiral is the reason of this cipher naming, since he used it in his personal correspondance

Task 3 - The space station that rocked (25 points)

You hear the heavy base line of 64 speakers from the next compartment. you walk in and the song changes to writing's on the wall, there is some strange code painted on the wall what could it mean?

Given :

RXZlbiAgaW4gc3BhY2Ugd2UgbGlrZSB0aGUgYnV0dGVyeSBiaXNjdXQgYmFzZS4gY3Rme0lfbGlrZV90aGVfYnV0dGVyeV9iaXNjdWl0X2Jhc2V9IC4gQWNjZXNzIHBhcnQgMzogWEQ=

Decoded (Base64) :

Even  in space we like the buttery biscut base. ctf{I_like_the_buttery_biscuit_base} . Access part 3: XD

Task 4 - What the beep is that? (25 points)

You hear beeps on the radio, maybe someone is trying to communicate? Flag format: CTF:XXXXXX

Given :

.. -. ... .--. . -.-. - --- .-. / -- --- .-. ... . / .-- --- ..- .-.. -.. / -... . / .--. .-. --- ..- -.. / --- ..-. / -.-- --- ..- .-. / . ..-. ..-. --- .-. - ... .-.-.- / -.-. - ..-. ---... ... .--. .- -.-. . -.. .- ... .... ..--- ----- ..--- .---- / .- -.-. -.-. . ... ... / -.-. --- -.. . ---... / .--- --...

Decoded (Morse Code) :

INSPECTORMORSEWOULDBEPROUDOFYOUREFFORTS.CTF:SPACEDASH2021ACCESSCODE:J7

Task 5 - The container docker (25 points)

You are now in the space cafe, the cake is in the container that should not be here. You can see random names on all the containers. What will Docker never name a container? Note: Please enter it as ctf{full_name}

Answer

Docker container will never named boring_wozniak, because of the logic (line 844 to 846) in file names-generator.go from the source code

Task 6 - There might be more cake (50 points)

They ate then cake and left a note with a secret algorithm to unlock the cake treasury. We saw it happening at exactly January 1, 2030 11:23:45 AM... are you the visionary that can figure out the PIN code?

Given the PIN generation algorithm :

int generatePin() {
    srand(time(0));
    return rand();
}

and also the required timezone be UTC

By adjusting the seeding long integer to UTC +0:00 (check here), you should be able to get the correct PIN (see task6.c on original writeup for more information)

Task 7 - Stars in space (30 points)

The treasury consists of cake hidden on stars in space.

Given :

* ****  * * * *** ***  **    *  *  * ****  * ** *  ** ***  ** ***  ** * *  *   ** *     *  * ** *  *   ** *     *   **  *   *****  **** *  ***  *  ** * *     * 

Decoded 1 (Substitution : * = 0, and ' ' = 1) :

0100001101010100010001100111101101101000011010010110010001100100011001010110111001011111011010010110111001011111011100110111000001100001011000110110010101111101

Decoded 2 (8-bit binary with no delimiter) :

CTF{hidden_in_space}

Flags

1. ctf{You_found_the_rot}
2. ctf{The_one_true_salad}
3. ctf{I_like_the_buttery_biscuit_base}
4. CTF:SPACEDASH2021
5. ctf{boring_wozniak}
6. 1376299761
7. CTF{hidden_in_space}

References

• Cyberchef [Task 1,3,4,7]
• Caesar Cipher Brute-Force Decoder [Task 2]
• Why boring wozniak will never be generated as a container name in docker [Task 5]
• EPOCH timezone checker [Task 6]
• About time_t struct in C [Task 6]
• About timegm function in C [Task 6]

Original writeup (https://github.com/GohEeEn/CTFs-Write-Up/blob/main/HackyHoliday2021/misc/Space_Snack/README.md).