Gaining Interactive Shells

Often when uploading a reverse shell on a webserver we are dealing with non-interactive shell. This means it doesn’t prompt us for user input or display output in real-time in a traditional terminal window.

The biggest problem with a non-interactive shell is that you can’t run su or sudo.

Useful ways to upgrade your shell to an interactive one:

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

When to use it: Almost always the first go-to if Python is available on the target. After spawning, run Ctrl-Z and then stty raw -echo; fg on your local terminal to fully fix arrow keys and job control.

echo 'os.system('/bin/bash')'

When to use it: When you can inject Python code but can’t directly execute shell commands.

/bin/sh -i

or

/bin/bash -i

When to use it: Works on minimal systems where Python or Perl might not be installed. Note the -i flag forces the terminal to be interactive.

perl -e 'exec "/bin/sh";'

When to use it: When Python isn’t available, but Perl is. This takes advantage of Perl’s exec function.

:!bash

When to use it: If you can edit files on the system and Vim is installed. This is often used in “local shell escape” scenarios.

SHELL=/bin/bash script -q /dev/null

When to use it: This command is very reliable if script is installed. Script spawns a fully interactive shell session, which fixes TTY issues

stty raw -echo && fg

When to use it: This resets your terminal to raw mode and resumes the background shell. You should use it when your shell has been suspended with Ctrl + Z.

Cheatsheet

Start by checking available interpreters:

which python3 python perl bash sh

Fix terminal controls after an upgrade:

Ctrl+Z

stty raw -echo

fg

reset

Tip: Try Ctrl + C, Ctrl + Z, and Tab completion to make sure the shell is fully interactive.