sam686@debian986:~$ env 'VAR=() { :;}; echo Bash is vulnerable!' 'FUNCTION()=() { :;}; echo Bash is vulnerable!' bash -c "echo Bash Test"
Bash is vulnerable!
bash: FUNCTION(): line 0: syntax error near unexpected token `)'
bash: FUNCTION(): line 0: `FUNCTION() () { :;}; echo Bash is vulnerable!'
bash: error importing function definition for `FUNCTION'
Bash Test

sam686@debian986:~$ foo='() { echo not patched; }' bash -c foo
not patched

sudo apt-get update
sudo apt-get install --only-upgrade bash
Unpacking bash (4.3-9.2) over (4.3-9) ...


sam686@debian986:~$ env 'VAR=() { :;}; echo Bash is vulnerable!' 'FUNCTION()=() { :;}; echo Bash is vulnerable!' bash -c "echo Bash Test"
Bash Test
sam686@debian986:~$ foo='() { echo not patched; }' bash -c foo
bash: foo: command not found