Stabilizing the Dump Shell

Hello All, This is my first blog that explains how to stabilize the shell in Linux.

While playing CTF Challenges, it is often to spawn a reverse shell on the target machine. Other than the ssh shell, every shell is a dump which often kills the reverse shell and this shell doesn’t give you the proper shell functionalities like tab completion, “su” command, clearing the terminal, etc. Sometimes, pressing “ctrl+c” completely kills your reverse shell.

Shell Stabilization prevents you from killing your reverse shell and adds proper shell functionalities.

Note: This post assumes you already have a reverse shell on the target machine.

Commands to upgrade a TTY dump shells

Python3

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

Bash

/usr/bin/script -qc /bin/bash /dev/null
(or)
/bin/sh -i

Perl

perl —e 'exec "/bin/sh";'
(or)
perl: exec "/bin/sh";

Ruby

ruby: exec "/bin/sh"

Lua

lua: os.execute('/bin/sh')

Then press ctrl+z to background the process.

Run the following command in the attacker machine,

Attacker Machine

stty raw -echo
fg
ENTER
ENTER

Run “stty raw -echo” and “fg” commands on the attacker machine, then click double ENTER. The reverse shell will be retrieved.

Victim Machine

export TERM=xterm
stty cols 132 rows 34

Set the terminal environment to the variable (e.g. xterm, xterm-256, etc)

All Done! Now you should have a stabilized bash shell that can tab complete, clear the screen, and use Ctrl+C.