The Void (Huntress CTF 2024)
Author: @JohnHammond#6971
When you gaze long into the void, the void gazes also into you…
Connecting to this results in the shell getting spammed with nothing. I redirected the output to a file, and it just kept growing and growing. Eventually I killed it and tried to see the hexdump, passing it to head to only see a bit of it. Strangely it was 1b 5b 33 30 3b 34 30 6d 20 being repeated over and over. The ascii view showed some brackets and ms - indicative of ANSI escape sequence. I did not feel motivated to decode it, so I asked ChatGPT. It gave me this breakdown:
1b: ESC (Escape character)[: Beginning of an ANSI control sequence30;40: Control codes for setting text colors30: Set text color to black40: Set background color to blackm: End of the control sequence20: A space character
It gave this gem: 's/\x1b\[[0-9;]*m//g'. Using this, I managed to sed the output file to remove the escape characters and extract any non sequence characters and it was just the flag, padded with plenty of spaces.