CTF: MBR - 486DX

MBR Capture the Flag Challenge

Album released: 15 May 2017

https://masterbootrecord.bandcamp.com/album/486dx

Secret

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

Analysis

It’s a Base64 encoded blob. Decoding it and looking at it with a hex editor I see a header with “JFIF”, indicating it is probably a JPEG.

Solution

test

But perhaps there’s more to it? Some embedded data in the JPEG?