A fully isolated VirtualBox environment with an intentionally vulnerable Ubuntu target — engineered for safe exploitation, privilege escalation practice, and hardening analysis without touching live systems.
A true security professional needs a safe, isolated place to fail, learn, and succeed. The Cyber Dojo is a fully isolated virtual laboratory built on VirtualBox with Host-Only adapters — creating a walled garden where traffic cannot leak to the LAN or internet under any circumstances.
The lab consists of two machines: a Kali Linux attacker and a custom Ubuntu Server target engineered with deliberate, realistic vulnerabilities that mirror common corporate misconfigurations.
The Ubuntu Server was built from scratch and hardened in reverse — intentional flaws were introduced methodically so each vulnerability could be exploited cleanly and the corresponding fix documented.
PermitRootLogin yes and PasswordAuthentication yes set in /etc/ssh/sshd_config. Weak user noob:password123 and root with trivial password created.PermitRootLogin no, and remove all default/weak accounts./var/www/html with guest ok = yes, writable = yes, and force user = root — any guest upload gains root file ownership on the web root.force user = root from all configurations.chmod u+s /usr/bin/find allows any user to invoke find with root-level execution via the -exec flag — trivially spawning a root shell.find / -perm -4000 -type f and apply least-privilege to all binaries.PermitRootLogin and password auth enabled — low-privilege account noob compromised. Foothold established as a standard user./var/www/html via SMB enumeration. Uploaded a PHP reverse shell through the open share. force user = root meant the file landed with root ownership — reverse shell executed via the web server./usr/bin/find with SUID bit set. Exploited via GTFOBins technique to spawn a root shell — privilege escalation complete.# Enumerate SUID binaries first find / -perm -4000 -type f 2>/dev/null # Exploit — spawns root shell via -exec /usr/bin/find . -exec /bin/sh -p \; # Confirm id uid=0(root) gid=0(root) groups=0(root)
Each vulnerability was documented with reproduction steps, impact analysis, and hardening guidance — producing a structured manual that can be used to rebuild the machine from scratch and re-test after remediation.