Posted on May 19, 2022
tl;dr: raid, disk reassembly


I didn’t solve this challenge during the CTF, i was just about to when the time ran out. But i wanted to do it because it was fun to play around with some raid-tools that i hadn’t done before.


Each challenge had a story tied to it, for this challenge it was:

Miyuki’s team stores all the evidence from important cases in a shared RAID 5 disk. Especially now that the case IMW-1337 is almost completed, evidences and clues are needed more than ever.
Unfortunately for the team, an electromagnetic pulse caused by Draeger’s EMP cannon has partially destroyed the disk. Can you help her and the rest of team recover the content of the failed disk? Download:

Attacking the challenge

Download the zip file, inside it there’s 3 .img files, where the disk3.img is much smaller than the other two. We’ll assume that this is the broken disk.

Create loop-devices for the .img files with losetup (included in kali).

More information about losetup:

Kali uses /dev/loop0-2 , for snapshot-reasons, so take the next in line.

sudo losetup /dev/loop3 disk1.img
sudo losetup /dev/loop4 disk2.img
sudo losetup /dev/loop5 disk3.img

To build a raid from those, we need a tool called mdadm

sudo apt install -y mdadm

And then to rebuild the raid, and assume that disk3.img is broken, but data can be rebuilt from the other two:

sudo mdadm --create --assume-clean --level=5 --raid-devices=3 /dev/md0 /dev/loop4 missing /dev/loop3

Mount the /dev/md0 disk, and copy out the pdf file we’re looking for.

mkdir /mnt/tmpraid
mount /dev/md0 /mnt/tmpraid
cp /mnt/tmpraid/*.pdf .

Open the PDF and behold the beautiful investigation: htb-ca22-igr1

Flag: HTB{f33ls_g00d_t0_b3_1nterg4l4ct1c_m0st_w4nt3d}