Mommy told you not to store your important files on those old diskettes. Can you repair the file?
Have you heard of magic numbers?
Any time I get a file from a CTF, the first thing I do is open it in a hex editor. When opening this file I see that the first four bytes are
DE AD BE EF, which is a classic magic number. Since I have worked with zip files in the past, I knew they started with
PK and then a version number. A quick google search got me the right values. So I replaced the
DE AD BE EF bytes with
50 4B 03 04 and was able to open the file.
This got us a smiling horse:
I opened this file with a hex editor and a search for the string
cm, yields our flag: