Like everything else, and more than most, good old DOS was especially susceptible to memory corruption vulnerabilities!
Lacking any mitigations whatsoever, it could truly have been a hacker's wonderland.
However, the exploitation of memory corruption vulnerabilities was not so well understood, and outside of mostly-just-annoying viruses, mayhem did not really manifest.
From our lofty position in the future, we can look back and change that!
This challenge is a peek into the vulnerability of DOS applications.
Go and learn what once was, and what hackers did not even understand until it was long gone.
NEW TO DOS?
Check out The DOS Dojo for more DOS shenanigans.
NOTE:
Files from /home/hacker/d:/ are copied to D: when you launch DOS.
You can copy files to the D: drive in DOS, and they should be synchronized out to /home/hacker/d:/ within a few seconds.
NOTE:
The flag is in C:\FLAG.TXT.
NOTE:
The challenge files are in /challenge, and the initial contents of the C: drive are in /challenge/c_files.
NOTE:
Launch the DOS VM by running /challenge/launch in Linux!
NOTE:
You can start this challenge in Privileged Mode and edit /challenge/c_files before starting the challenge, allowing you to modify VULN.C and AUTOEXEC.BAT for debugging.