This is a write-up for Pang challenge from NahamCon CTF.
What we got in this challenge is a file. After downloading the file and checking its type, we found it’s a png image.
But if we tried to open it with any image viewer, it gives the below error.
Error: Fatal error reading PNG image file: IHDR: CRC error
I googled the above error and found that the png image is missing something and needs a repair. Then, I searched for a tool to repair the png image and I found a tool on github to check and repair png images which I found very useful.
https://github.com/sherlly/PCRT
After running the tool on the image, it found errors and prompted to repair it and finally it repaired the image.
Let’s see the new repaired image output.png
Yes, it has the flag and we can run image2text tool mentioned below to get the text out of the image. It’s not that accurate, but at least you won’t rewrite this long flag from the beginning, just a few characters to write or replace.
https://github.com/prabhakar267/image2text
flag{wham_bam_thank_you_for_the_flag _maam}