Bash Breakout

Breaking out of a restricted shell is a significant step in ethical hacking and penetration testing. However, sometimes you find yourself in a limited or non-interactive shell environment where essential features like command history navigation and screen clearing don't work. In such cases, upgrading to a fully interactive TTY shell becomes crucial. Here are some effective methods to enhance your shell environment.

1. Python Method:

Python is often a savior in shell environments. If it's installed on the system, use it to spawn a bash shell:

python -c 'import pty; pty.spawn("/bin/bash")'

For Python 3:

python3 -c 'import pty; pty.spawn("/bin/bash")'

Or, for a more enhanced experience with Python 3:

python3 -c 'import pty; pty.spawn(["/bin/bash", "--rcfile", "/etc/bash.bashrc"])'

2. Script Command:

The script command is useful for spawning a new shell session:

script /dev/null

This starts a new shell session and logs it, which can provide a more functional environment.

3. Using RLWrap:

RLWrap allows for editing of keyboard input for any command. It's particularly useful with netcat:

rlwrap nc -lvnp [port]

4. Stty Settings:

Adjusting terminal settings can be helpful:

stty rows [num] columns [num]

Use stty -a on your local machine to find the correct values.

5. Reconnecting the Shell:

After spawning a TTY, you can fine-tune it:

stty raw -echo; fg

Background the shell with Ctrl+Z, then run this command.

Conclusion:

While these methods offer various ways to upgrade to an interactive shell, remember that their success depends on the target system's configuration.