Bash hero

Prerequisites & Requirements

• Linux Privilege Model: Understanding how sudo permissions and the /etc/sudoers file can be leveraged to run scripts as a different user.
• Bash Syntax & Logic: Familiarity with conditional statements and regex matching in shell scripts.
• Linux File System Navigation: Ability to explore directories and identify non-standard scripts or binaries.
• Shell Expansion Techniques: Knowledge of how Bash interprets characters like braces {} and backticks ` to execute commands without standard spacing. 

What will you learn?

• Restricted Shell Escapes: Learning how to "jailbreak" from a script that limits user input through blacklisted characters.
• Bypassing Input Filters: Using Brace Expansion and Command Substitution to circumvent filters that block spaces or specific alphanumeric characters.
• Sudoers Exploitation: Recognizing security risks when a script is granted NOPASSWD root privileges.
• Source Code Auditing: dentifying logical flaws in a script's sanitization function (e.g., blacklisting vs. whitelisting).

Tools

• None