MetaRed 2022 4th STAGE - Find the message
Find the message is a crypto challenge that was part of the MetaRed CTF 2022 (4th STAGE).
Sy@t{N_f0yq13e fubBg$, n uNpx3E t!irf 3agrE}
We were give no other information.
First look
To solve this challenge, we need to find the encryption method used.
The website dcode.fr pointed us to the Vigenere cipher
.
Solution
Now we had to find the key.
Using the same website www.dcode.fr/vigenere-cipher, with the Knowing a plaintext word
option, and word FLAG
as a first guess, got us these results:
YLAJBV Un@t{E_e0ds13t flaGi$, c uEoc3G i!iie 3figE}
NNTHC Fl@a{G_d0ld13l ysoOn$, g sAce3X r!vem 3teeR}
ENNNKM Ol@g{A_v0mm13r shrPc$, a hAfl3A g!vev 3oceR}
YLDGFU Un@q{H_a0es13t cowHi$, c rHkd3G i!fla 3gigB}
AJBV Sp@s{S_f0pp13j flaGg$, e tSpo3D y!iie 3fgiD}
TTCNNS Zf@r{A_s0gx13l dhoJn$, u sAcf3L a!ges 3inyC}
NNTHNQ Fl@a{G_s0id13r mnoLt$, a bGch3R g!pks 3kteL}
...
Turns out that FLAG
is not in the message. But we weren’t that far off. NNTHNQ
seems to be very close.
The first and second letter of our plaintext should be F
and L
(from FLAG{...
) and the first two letters of NNTHNQ
are N
which gave us Fl@a{G_s0id13r mn...
.
So we tried the Knowing the Key/Password
option with N
:
Fl@g{A_s0ld13r shoOt$, a hAck3R g!ves 3nteR}
That’s it!
Flag
The flag is “Fl@g{A_s0ld13r shoOt$, a hAck3R g!ves 3nteR}”.