A file with a damaged first byte
The file command calls this challenge plain data, but the bytes after the first one look familiar. Read the header with xxd, name the format, and find which byte was changed.
Briefing
The challenge is ~/challenge/mystery.bin. The author says "one byte stands between you and the picture".
Formats start with fixed magic bytes. PNG starts with 89 50 4E 47 0D 0A 1A 0A, which is .PNG followed by line-ending bytes. If one of them is wrong, file no longer recognises it.
ctf-box · CTF warm-ups
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