BSidesSF 2023 Writeups: id-me (easy file identification challenge)

id-me is a challenge I wrote to teach people how to determine file types without extensions. My intent was to use the file command, but other solutions are absolutely possible!


I designed id-me to be a fairly straight forward “identify this file” challenge. The user is given four files, and they are tasked with reading part of the flag from each of them.

I’d personally use the file command on Linux:

$ file *
file1: ASCII text
file2: JPEG image data [...]
file3: PDF document, version 1.4
file4: Zip archive data, at least v2.0 to extract, compression method=deflate

But lots of other ways exist, including simply opening them in the Chrome browser.


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