How To Check Vulnerable to Shellshock in Mac or Linux Machine

You can test your system by running this test command from Terminal:

env x='() { :;}; echo vulnerable' bash -c 'echo hello'

If you're not vulnerable, you'll get this result:

bash: warning: x: ignoring function definition attempt bash: error importing function definition for `x' hello

If you are vulnerable, you'll get:

vulnerable hello

You can also check the version of bash you're running by entering:

bash --version

If you get version 3.2.51(1)-release as a result, you'll need to update. Many Linux distributions already have patches available, so you can follow these instructions to update your system.