After repairing the height or running StegSolve on the "Gray Bits" or "Red 0" planes, a text string (the flag) typically appears at the bottom of the image or in a separate output window. It usually follows the format CTF{...} or FLAG{...} .
The most common solution for this specific file involves . Many CTF creators intentionally modify the height or width values in the PNG header so the image doesn't render correctly or hides the flag at the bottom. Tool : Hex Editor (like HxD or hexedit ). 2022-06-03 11-32-03~2.png
: Run strings 2022-06-03 11-32-03~2.png . In many versions of this challenge, the flag or a hint is appended to the end of the file in plain text, past the IEND chunk. After repairing the height or running StegSolve on
: Use the file command in Linux to confirm it is indeed a PNG image. Many CTF creators intentionally modify the height or
: Locate the IHDR section (usually starts at offset 0x0C ). The four bytes following IHDR are the width, and the four after that are the height.
If repairing the header doesn't reveal the flag, the next step is checking for hidden data:
: If you change the dimensions manually, the CRC (Cyclic Redundancy Check) at the end of the chunk will be invalid. You can use a tool like PCRT (PNG Check & Repair Tool) to automatically calculate the correct dimensions based on the existing CRC. 4. Steganography Check