Introduction #

This is my first time participating in wargames.my.

Due to some time management issues, I started to solve the challenges 3 hours before the competition ends. Nevertheless, here are my write-ups for 2 easy challenges.

The DCM Meta (Easy) #

This challenge was supposed to be easy, but I managed to not solve it because one minor error in my code. 🤦🏻 (I set i < 31 , which made my flag length is less by 1)

Here is the corrected code for your reference.

scramble = "f63acd3b78127c1d7d3e700b55665354"

sequence = [25, 10, 0, 3, 17, 19, 23, 27, 4, 13, 20, 8, 24, 21, 31, 15, 7, 29, 6, 1, 9, 30, 22, 5, 28, 18, 26, 11, 2, 14, 16, 12]

# print(len(scramble))

i = 0 
seq_i = 0
solved = []

while i < 32:
    solved += scramble[sequence[seq_i]]
    seq_i += 1
    i += 1
    

solved = "".join(solved)
print(f"wgmy{{{solved}}}")
    

Unwanted Meow (Medium, but actually easy) #

After inspecting the bytes in the attached file, there are a lot of “meow"s which corrupts the file. I tried replacing them using hexed.io but it will take a long time.

Then I realized.. why not use Cyberchef?

By using the “Find/Replace” function and using the magic wand immediately, a sorta distorted image is recovered. I tried to submit the flag consisting of the viewable letters, and it’s not the correct flag.

The reason of this phenomenon is there are still “meow"s concealed due to the challenge creator’s smart method of wrapping a meow within another meow.

Finally the image is restored successfully.

Conclusion #

I lied actually about the starting time in the introduction. I was stuck doing the blockchain challenge in the morning causing me to give up midway. However, I continued to solve challenges at night due to the love of the game (plus I can’t sleep after a long nap in the afternoon)

See ya!