ctf-writeup/2023/AmateursCTF 2023/zipper

zipper

Stare into the zip and the zip stares back.

About the Challenge

We were given a zip file that contains a lot of txt files

How to Solve?

First, you can get the first part by using exiftool and then check comment metadata

Part 1: amateursCTF{z1PP3d_

And then to obtain the second part, we need to check the information about the zip file first by using zipinfo command

Why are there two directories with the same name, and why does the second one have 17 bytes in it? If you unzip it manually, one of the directories will be overwritten; that's why we need to extract it differently.

To extract the flag, I created a python program to extract the file using a file_ as a prefix

import zipfile
z = zipfile.ZipFile('flag.zip')
for i, f in enumerate(z.filelist):
    f.filename = 'file_{0:03}'.format(i)
    z.extract(f)

And then use strings and grep to find the second part

Part 2: in5id3_4_

For the third part, you can use exiftool again and find Zip File Comment metadata

And for the last part, when you unzip the file you will notice there is a file with the same name

Open it and you will obtain the flag

amateursCTF{z1PP3d_in5id3_4_laY3r_0f_Zips}