Copy-paste this line of text into a bash window

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

If the reply comes back as:

vulnerable hello

or

vulnerable
hello


Then your version of bash is vulnerable to shellshock. Most distributions have already pushed out a new version of bash. My Ubuntu machines updated yesterday.

If you use Cygwin, then you need to check there to. Cygwin bash 4.1.10 is definitely vulnerable, but 4.1.11 is not.

If your version of bash is not vulnerable the output will be:

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

How To Check If Your Mac or Linux Machine Is Vulnerable to Shellshock.

Related articles

• How To Check If Your Mac or Linux Machine Is Vulnerable to Shellshock
• Bug in *nix Bash dubbed ‘shellshock’
• ‘Bigger than Heartbleed’ Shellshock flaw leaves OS X, Linux, more open to attack
• ‘Bigger than Heartbleed’ Shellshock flaw leaves OS X, Linux, more open to attack
• How to Protect your Server Against the Shellshock Bash Vulnerability
• What is the Bash bug, and how do I prevent my systems from being Shellshocked?
• Shellshock vulnerability roils Linux server shops
• Meet Shellshock, the new Heartbleed
• Shellshock: the ‘Bash Bug’ That Could Be Worse Than Heartbleed by Stan Schroeder of Mashable
• ‘Bigger than Heartbleed’ Shellshock flaw leaves OS X, Linux, more open to attack then ever!