ShadowCTF Write-up

Raj Upadhyay
4 min readJan 27, 2021

Recently I played ShadowCTF. Let’s see how I was able to solve few challenges.

Cryptography

All the cryptography challenges were awesome. ( Google search and Decodefr are my helping hands in Cryptography challenges.)

Valhalla

So let’s see what is inside “File”

So we have some wired text in front of us. So as “rune” is mentioned in the description of the challenge let’s google search it.

So I found this link which is useful to decode it. (https://www.dcode.fr/elder-futhark)

Flag: ShadowCTF{odin_was_here}

Rick and morty on adventure

So let’s open the file and see what we have been given.

After few minutes of google search finally able to find that, this can be decoded with “GRAVITY FALSS BILL CIPHER DECODER” (Link: https://www.dcode.fr/gravity-falls-bill-cipher)

Flag:ShadowCTF{mortylikessnakejazz}

Monk

So let’s open the given file.

In the description ‘temple’ looks like a keyword. I spend around 1-hour then I was able to solve this challenge. Finally, this site “https://asecuritysite.com/challenges/monk” helped me to decode it.

After decoding we get a decimal number like this.

66 111 119 95 84 48 95 84 104 51 95 71 79 100

So we need to convert it to ASCII.

Flag: ShadowCTF{Bow_T0_Th3_GOd}

What are Semaphores processes?

So let’s open the given file.

Another symbol cipher.

So I did a google search like this “trouser cipher” and got the first link:https://www.dcode.fr/semaphore-trousers-cipher

Flag: ShadowCTF{thankyouhacker}

Colored….P

So Let’s open the given file.

So it’s a “color cipher” so it can be decoded by simple google search.

So with help of the above image, I have decoded the image.

Flag:ShadowCTF{HELL_CS}

DORAEMON

So we have been given the following Cipher:

RE O R LA MI M O N H LA DO K 3 RE

So in the description, we can see “music notes” are written. So with a google search, I was able to find that this cipher was “Music Notes Cipher”. (Link: https://www.dcode.fr/music-notes)

So,

Flag: ShadowCTF{D_O_R_A_E_M_O_N_H_A_C_K_3_D}

MISC

Riddle

So the first thing I searched is “Betsy plumleigh teape” on google.

So we can “Betsy plumleigh teape” is mother of “Charles Babbage” and “Charles Babbage” is the founder of COMPUTER.

So same way we need to find, who is father of “COMPUTER SCIENCE”

So now we just need to find the name of “Turing’s mother”

Flag: ShadowCTF{Ethel_sara_stoney}

Git is Fun

So Let’s visit the link

So nothing interesting. So let’s check all commits.

So let’s start from the first commit and see we can find the flag.

Here is your secret authentication key ONUGCZDPO5BVIRT3LEYHKX3BKIZV6VBUGAYGYM3EPU======

So it looks like a base32 string let’s decode it.

So it’s not a flag. So i opened all the commits and finally able to find one interesting file (Flag).

PFXGO2TVMNEVUTD3IUYGCX3NGBNF66SOGF4V6TBBORAFEUTFPU======

Again we got a Base32 string so let’s decode it.

So it looks like Caesar cipher So let’s decode it.

Flag: shadowCTF{Y0u_g0T_tH1s_F!n@LLy}

Thank you for reading.

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Raj Upadhyay

Pursuing M. Tech. in Cyber Security and Incident Response. #LoveToPlayCTF #infosec #cybersecurity