CTF: MBR C​:​\>CHKDSK /F

MBR Capture the Flag Challenge

Album released: 22 Sep 2016

https://masterbootrecord.bandcamp.com/album/c-chkdsk-f

Secret

Process started on 12/09/2016 at 8.41
Process completed on 21/09/2016 at 00.38
Report released on 22/09/2016 at 16.21

EnCt22c62d8d00a89d36908e9015ae37997d3c7ad246a2c62d8d00a89d36908e9015a1oP6qx4YRwLsBuHI41cIJP4+e/69xyBAGJIxfloS/Oq7/cpvKOb9PVojA0iOlrIyWcdBRSqAnVpV2EnF75tADlbmgkOkgkJHPOgxwMmSVmjwXqutPdIFF5DXcsB8X/URs0qgEuxgK3N5pUuJorJED/O4Yg1xz1E=IwEmS

Analysis

Looks sort of like Base64, although I do see a rather low-entropy substring: 22c62d8d00a89d36908e9015ae37997d3c7ad246a2c62d8d00a89d36908e9015a1 that might be hexadecimal, and there’s some characters after what would be padding in Base64. It could also just be a coincidence as well.

I receive errors trying to decode it. I tried removing the substring above as well, but no dice. It does output some binary though, but I do not see any headers I recognize, nor does the file command in Linux.

After looking for hints, this is weird mix of Base64 and some other hexadecimal or something. Some home-rolled encryption, used by: https://encipher.it/