NahamCon2021 CTF - Buzz - Writeup

Introduction

Today we're doing a CTF writeup for the Buzz challenge from the NahamCon2021 CTF. Buzz is a file compression challenge and after we started the challenge we downloaded the associated file we checked what kind of file it was:


file buzz


Seems to be a compressed file, but no specific type is identified. We try decompressing it with Gzip, a common compression program:

gzip -d buzz


Gzip won't interact with any files that don't have the .gz file extension, so let's add it:

mv buzz buzz.gz


Now let's try again:

gzip -d buzz


Seems to have worked. Let's check the buzz file's type again:

file buzz


It worked. Let's read the file:

cat buzz


Summary

The downloaded file appeared to be compressed upon inspection. Upon renaming the file to add a common file-compression extension, we were able to decompress the file and read it, accessing the objective flag string.

Finish





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