Description

The login shell is a custom “UPPERCASE SHELL” that converts all input to uppercase before executing it. Standard commands like cat become CAT which are not found. The goal is to escape to a normal shell.

Overview

• $0 is a special shell variable that expands to the name (or path) of the current shell.
• In an interactive shell, $0 is the shell binary itself (e.g., /bin/sh).
• Typing $0 at the uppercase shell prompt executes /bin/sh, spawning a standard shell.
• The uppercase shell converts $0 to $0 (dollar and digit are not letters), so it reaches execve unchanged.

Solution

>> $0
$ whoami
bandit33
$ cat /etc/bandit_pass/bandit33

Password

odHo63fHiFqcWWJG9rLiLDtPm45KzUKy