• Category: misc
  • Difficulty: beginner
  • Author: jscarsbrook

Dear bart,

Nobody likes having to download large disk images for CTF challenges so this time we’re giving you a disk over the network!

Regards,
jscarsbrook

AU: nc chal.2025.ductf.net 30016
US: nc chal.2025-us.ductf.net 30016


Solve

  • nc chal.2025.ductf.net 30016 returned NBDMAGICIHAVEOPT
  • Loaded the NBD kernel module: sudo modprobe nbd
  • Connected with: sudo nbd-client -N root chal.2025.ductf.net 30016 /dev/nbd0
  • Mounted the filesystem: sudo mkdir /mnt/nbd && sudo mount /dev/nbd0 /mnt/nbd
  • Navigated and copied the flag image locally: cp /mnt/nbd/path/to/flag.jpg ~/flag.jpg
  • Opened the image to read the flag: DUCTF{now_you_know_how_to_use_nbd_4y742rr2}