How to protect your CentOS server from the Shellshock exploit

Shellshock is quite a serious security hole found a couple of days ago in Bash; to check whether your CentOS server is vulnerable run the following in a terminal:
env VAR='() { :;}; echo Shellshock vulnerable!' bash -c "echo Bash Testing"
If your system is vulnerable, you will see:
Shellshock vulnerable! Bash testing
If it is not vulnerable, you will see:
bash: warning: VAR: ignoring function definition attempt bash: error importing function definition for `VAR’ Bash testing
If you are vulnerable, you can update bash by running the following:
sudo yum update bash
Once the update has finished, run the code to check your vulnerability again and it should be sorted.



How to protect Debian from the Shellshock exploit

Shellshock is quite a serious security hole found a couple of days ago in Bash; to check whether your Debian server is vulnerable run the following in a terminal:
env VAR='() { :;}; echo Shellshock vulnerable!‘ bash -c “echo Bash Testing”
If your system is vulnerable, you will see:
Shellshock vulnerable! Bash testing
If it is not vulnerable, you will see:
bash: warning: VAR: ignoring function definition attempt bash: error importing function definition for `VAR’ Bash testing
If you are vulnerable, you can update bash by running the following:
sudo apt-get update && sudo apt-get install --only-upgrade bash
Once the update has finished, run the code to check your vulnerability again and it should be sorted.



How to protect Ubuntu against the Shellshock exploit

Shellshock is quite a serious security hole found a couple of days ago in Bash; to check whether your Ubuntu server is vulnerable run the following in a terminal:  
env VAR='() { :;}; echo Shellshock vulnerable!‘ bash -c “echo Bash Testing”
  If your system is vulnerable, you will see:  
Shellshock vulnerable! Bash testing
  If it is not vulnerable, you will see:  
bash: warning: VAR: ignoring function definition attempt bash: error importing function definition for `VAR’ Bash testing
  If you are vulnerable, you can update bash by running the following:
sudo apt-get update && sudo apt-get install --only-upgrade bash
  Once the update has finished, run the code to check your vulnerability again and it should be sorted. NOTE! Only the currently-supported versions of Ubuntu will get the bash update – if you are running anything older (e.g. 13.04, 13.10 or anything older that isn’t a still-supported LTS release) you will need to update your Ubuntu install to have the above work.