chunkies

The given PNG file was corrupted. We easily see the missing \x89 at the top of the file before the PNG chunk. Then browsing the image again we see the IADT and the INED chunks. Using

sed -i 's/IADT/IDAT/g' fix.png
sed -i 's/INED/IEND/g' fix.png

is enough to fix every chunks. Last error is a CRC corruption as pngcheck shows:

$ pngcheck -v fix.png
...
CRC error in chunk IHDR (computed 5a7b8dc, expected 5a9b8dc)
...

Let's manually change the value from what it gets to what it expects, and get our flag!

shaktictf{Y4YyyyY_y0u_g0t_1T}

Original writeup (https://github.com/Ewael/CTFs/tree/master/2021/ShaktiCTF/Forensics/chunkies).