Sunday, March 31, 2019

Bit Shifting: Cal Poly FAST CTF Challenge 11


File: https://raw.githubusercontent.com/mfput/CTF-Questions/master/file11.txt
Question: Find the flag in this text document!
Hint: If you are having trouble with this bit, shift your focus.
Answer: fastctf{a_bit_tricky}
In this challenge we are given a text file with some scrambled data.



The file is definitely a text file. However we can’t make any sense of it looking at it in a text editor. We need to use a hex editor to look for more clues.



Even in a hex editor is still looks like gobbledygook. Without any hints, this was a hard challenge. The hint states “If you are having trouble with this bit, shift your focus.” I use far too many puns with my hints, at least I have fun with them. Bit-Shifting involves shifting every bit in the file. We can do this with a hex editor called WinHex from X-Ways forensics (http://www.winhex.com/winhex/).
By shifting the bits to the left once, the file is displayed normally.




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