BroncoCTF : Magic Ways Writeup

Short summary

A BroncoCTF writeup where a PNG file was deliberately corrupted at the byte level. The repair required three passes: restoring the PNG magic-byte signature (DEADBEEF replaced with 89 50 4E 47...), fixing a zeroed height field in the IHDR chunk, and recomputing the IHDR CRC32 checksum. Once repaired, the image displayed the flag as plain text.

• •PNG magic bytes replaced with DEADBEEF — restored to standard 8-byte signature
• •IHDR height field zeroed out — patched to match width (500px)
• •IHDR CRC32 checksum recomputed in Python after header edits

Generated with AI, which can make mistakes.