CDDC'23: Owner of the dog chew

This was a pretty interesting steganography challenge which required the analysis of strings and using binwalk.

The Challenge

Found a piece of bone on the ground. Let's find the owner.

The file given was the following image:


Looking into the image properties:

Image Size

It was 655kB, which seemed a little too large for a file as small as this.


The first thing I did was to look at the strings. Scrolling down to the end, I could see this:

pw : i'm_hungry

Seems like this involves another image file and a password. Next, I used binwalk to try and extract any hidden files:

kairos@pop-os:~/Downloads/Owner_of_the_dog_chew$ binwalk -e cddc2023_image.png 

0             0x0             PNG image, 1280 x 640, 8-bit/color RGBA, non-interlaced
41            0x29            Zlib compressed data, best compression
94485         0x17115         Zip archive data, encrypted at least v2.0 to extract, compressed size: 560398, uncompressed size: 561761, name: cddc2023_puppy.jpg
655031        0x9FEB7         End of Zip archive, footer length: 22

Seems like we got a zip file! Looking at the output files, I could see a password-protected zip file. Using the password above, I could then unzip it.

Unzipping it gave an image: Image

Once again, I tried to look at strings. And sure enough, it got us our flag!