PART 1 — Creating the chroot Jail Step 1 — Open Ubuntu Terminal

Login to Ubuntu.

Open Terminal.

Step 2 — Update Ubuntu

Run:sudo apt update

It will ask your password.

Example

[sudo] password for student:

Enter your password.

Step 3 — Install BusyBox Static

Run

sudo apt install -y busybox-static

Wait until installation finishes.

Step 4 — Verify BusyBox

Run

ls /bin/busybox*

You should see something like

/bin/busybox /bin/busybox-static

If only /bin/busybox exists, don’t worry yet—we’ll verify the correct path in the next step.

Step 5 — Create the Jail Folder

Run

mkdir -p ~/chroot_jail/bin

Check

ls ~/chroot_jail

Output

bin Step 6 — Copy BusyBox

First check where BusyBox is installed:

which busybox

or

ls -l /bin/busybox*

If /bin/busybox-static exists:

cp /bin/busybox-static ~/chroot_jail/bin/sh

If only /bin/busybox exists:

cp /bin/busybox ~/chroot_jail/bin/sh

Verify

ls ~/chroot_jail/bin

Output

sh Step 7 — Create Secret File

Run

echo “FLAG{CHROOT_IS_NOT_A_SECURE_SANDBOX_1206}” | sudo tee /host_secret.txt

Verify

cat /host_secret.txt

Output

FLAG{CHROOT_IS_NOT_A_SECURE_SANDBOX_1206} Step 8 — Enter the Jail

Run

sudo chroot ~/chroot_jail /bin/sh

If successful your prompt changes.

Congratulations!

You are now inside the jail.

PART 2 — Explore the Jail Step 9 — Check Current Directory

Run

pwd

Output

/ Step 10 — List Files

Run

ls -la /

Output

bin

Only the jail contents are visible.

Step 11 — Try Escaping

Run

cd ../../..

Then

pwd

Output

/

You cannot escape.

Step 12 — Try Reading the Secret

Run

cat /host_secret.txt

Output

cat: can’t open ‘/host_secret.txt’: No such file or directory

Success!

The host file is hidden.

Step 13 — Exit

Run

exit

You are back to Ubuntu.