MetaRed 2022 5th STAGE - hidden word
hidden word is a crypto challenge that was part of the MetaRed CTF 2022 (5th STAGE). We were given the string:
ACTCATGAG CCCOTTGATAACAATCTGCGCGTTG AGTATTACAUGCGACTATTOAAT ATAAAT ACCCATGAA TGGOAGACTGGAT ATTTCA TGCOATGCCTCTCATTTGTGCGACTGAGGAC ACTCATGAG TTCTTGGCGGGG ATATCG TGGGCACGC AACGAGACTTGGGAAGAAAAC CGCUTCCTCTATCGCA GCCAACGAC UAAGCGTGCGATTAATGAA CATGCATCC TGTGCGUTCCGAGGAT GCC TGCOATGATGOACCATCOAAC ATCAAT ACCCATGAG TGGOCGACTCGAC
and the following hint:
the format the flag is: flag{WORDFIND}
Solution
We took the same approach as the last MetaRed CTF (Find the message) to solve this challenge.
First we asked dcode.fr to identify the cipher. It identified it as a Codons (Genetic Code) cipher.
Using the Automatic Detection
option, we got the following result:
Method | Decoded text |
---|---|
RNA→A.A₁ |
ACTCATE POTTGATNAATCTACGTTG AGTATTTCDTATTOAAT ATKT TCATE TGGORCTGT ATTTCA TGCOATATCTCATTTGTAACTED ACTCATE TTCTTGGG ATATCG TGHGC NEACTTGKKAC RUTCCTCTATRA AND *ATAATTAATE CATATCC TGTAUTPRAT A TGCOATGATGOTATCON ATQT TCATE TGGORCTRC |
DNA→A.A₁ |
THE POLITICAL SITUATION IN THE WORLD IS CO(M/Start)PLICATED THE FLAG IS WAR NETWEEN RUSSIA AND UKRAINE HAS CAUSED A CO(M/Start)(M/Start)OTION IN THE WORLD |
A.A₃→A.A₁ |
ACTCATGAG CCCOTTGATAACAATCTGCGCGTTG AGTATTACAUGCGACTATTOAAT ATAAAT ACCCATGAA TGGOAGACTGGAT ATTTCA TGCOATGCCTCTCATTTGTGCGACTGAGGAC ACTCATGAG TTCTTGGCGGGG ATATCG TGGGCACGC AACGAGACTTGGGAAGAAAAC CGCUTCCTCTATCGCA GCCAACGAC UAAGCGTGCGATTAATGAA CATGCATCC TGTGCGUTCCGAGGAT GCC TGCOATGATGOACCATCOAAC ATCAAT ACCCATGAG TGGOCGACTCGAC |
… | … |
The DNA→A.A₁
method gave us a readable text that said:
… THE FLAG IS WAR …
Flag
The flag is “flag{WAR}”.