How to Protect Your Server Against the Shellshock Bash Vulnerability

Ubuntu now has the latest version of Bash sent out to their repositories. More info here:

http://people.canonical.com/~ubuntu-security/cve/2014/CVE-2014-7169.html

Thanks for this. Fixed it on my home computer and remote server. Awesome!

After update, is there any need to restart anything ??

I am with CentOS 6.5 x32

Hey Guys,

I just checked & updated the path on one of our production server.

After doing a “yum update bash”, rechecked:

env VAR=‘() { :;}; echo Bash is vulnerable!’ bash -c “echo Bash Test”

It simply gave below output:

Bash Test

Is this still vulnerable or patches updated? Please suggest.

Cheers, Vasu

Here’s Puppet code to patch it on CentOS:

exec { 'patch_shellshock_security_hole':
  command => "/usr/bin/yes | /usr/bin/yum update bash; touch /root/shellshock_bug_has_been_patched",
  creates => '/root/shellshock_bug_has_been_patched',
}

I have just tested this code and it worked fine on CentOS 6.4.

Ross

Same for Ubuntu 13.10?

i have 4.5.1(1) on 2 Ubuntu Servers. Does that mean not vulnerable? Test says otherwise. You state 4.3 is the latest.

I think, even if it’s not vulnerable, it’s a good idea to update bash to lastest version

I have Ubuntu 12.10 that is not more supported… what the best way to upgrade?

I hadn’t touched my droplet in quite a while - turns out I’m on 12.04 which has been EOL’ed and can’t seem to be updated. Any suggestions on how to handle this?

The CentOS yum repository has the fix. I just installed it on my CentOS 6.5 droplets.

Not so fast! Give it a try, still vulnerable!

env -i X=' () { }; echo hello' bash -c 'date'

https://shellshocker.net/

Thank you Digital Ocean, I am very happy with your hosting company :)

if you have some old / EOL release, this code may help you.

it requires you to have a compiler, patch & make, as such you may need to install these packages

for Ubuntu you can do

for CentOS/variants

(you may uninstall them afterwards if you no longer need)

after that, you can install bash from scratch, follow these commands (taken from the internet somewhere)

can first “cd /tmp” or start in any directory of your choice; must be executed as root [updated 2014-09-27 0900 EST [GMT-0500] now 26 patches instead of 25] [updated 2014-09-28 0900 EST [GMT-0500] now 27] [updated 2014-10-01 1400 EST [GMT-0500] now 28] [updated 2014-10-02 2300 EST [GMT-0500] now 29]

mkdir src
cd src
wget http://ftp.gnu.org/gnu/bash/bash-4.3.tar.gz
#download all patches
for i in $(seq -f "%03g" 0 30); do wget     http://ftp.gnu.org/gnu/bash/bash-4.3-patches/bash43-$i; done
tar zxvf bash-4.3.tar.gz 
cd bash-4.3
#apply all patches
for i in $(seq -f "%03g" 0 30);do patch -p0 < ../bash43-$i; done
#build and install
./configure && make && make install
cd .. 
cd ..
rm -r src

after this you should have the newest bash installed on your system

run the test again to check yourself

env VAR='() { :;}; echo Bash is vulnerable!' bash -c "echo Bash Test"

you should be good to go now!

To update from an older version of ubuntu (e.g. saucy), run this first:

sudo sed -i 's/saucy/trusty/g' /etc/apt/sources.list

That will update your sources to the newer ones. It might cause some incompatibility eventually, but it let me fix this problem for now.

I did the update and now can no longer SSH into my droplet. Anyone have any thoughts?

For people using ServerPilot to manage servers running PHP and WordPress sites, your servers are already patched. More info here:

https://www.serverpilot.io/blog/2014/09/25/bash-shellshock-security-updates.html

Ubuntu here… 4 droplets. Worked for versions 12.04 and 14.04 but not working in version 13.10

after running the apt-get command

… bash is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 84 not upgraded.

but vulnerability still there based in the test for version 13.10 as i said.

Thanks for making it easy. Just two commands, one to see that I need a fix and one to fix it. All done! I’m no linux guru, I just want to run a wordpress server!

I have some droplets with:

Distributor ID: Ubuntu Description: Ubuntu 12.10 Release: 12.10 Codename: quantal

And they don’t update. What i need to do so?

i mean, threre wont be a patch for this (others) version?

The CentOS yum repository has the fix. I just installed it on my CentOS 6.5 droplets.

Not so fast! Give it a try, still vulnerable!

env -i X=' () { }; echo hello' bash -c 'date'

https://shellshocker.net/

Thank you Digital Ocean, I am very happy with your hosting company :)

if you have some old / EOL release, this code may help you.

it requires you to have a compiler, patch & make, as such you may need to install these packages

for Ubuntu you can do

for CentOS/variants

(you may uninstall them afterwards if you no longer need)

after that, you can install bash from scratch, follow these commands (taken from the internet somewhere)

can first “cd /tmp” or start in any directory of your choice; must be executed as root [updated 2014-09-27 0900 EST [GMT-0500] now 26 patches instead of 25] [updated 2014-09-28 0900 EST [GMT-0500] now 27] [updated 2014-10-01 1400 EST [GMT-0500] now 28] [updated 2014-10-02 2300 EST [GMT-0500] now 29]

mkdir src
cd src
wget http://ftp.gnu.org/gnu/bash/bash-4.3.tar.gz
#download all patches
for i in $(seq -f "%03g" 0 30); do wget     http://ftp.gnu.org/gnu/bash/bash-4.3-patches/bash43-$i; done
tar zxvf bash-4.3.tar.gz 
cd bash-4.3
#apply all patches
for i in $(seq -f "%03g" 0 30);do patch -p0 < ../bash43-$i; done
#build and install
./configure && make && make install
cd .. 
cd ..
rm -r src

after this you should have the newest bash installed on your system

run the test again to check yourself

env VAR='() { :;}; echo Bash is vulnerable!' bash -c "echo Bash Test"

you should be good to go now!

To update from an older version of ubuntu (e.g. saucy), run this first:

sudo sed -i 's/saucy/trusty/g' /etc/apt/sources.list

That will update your sources to the newer ones. It might cause some incompatibility eventually, but it let me fix this problem for now.

I did the update and now can no longer SSH into my droplet. Anyone have any thoughts?

For people using ServerPilot to manage servers running PHP and WordPress sites, your servers are already patched. More info here:

https://www.serverpilot.io/blog/2014/09/25/bash-shellshock-security-updates.html

Ubuntu here… 4 droplets. Worked for versions 12.04 and 14.04 but not working in version 13.10

after running the apt-get command

… bash is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 84 not upgraded.

but vulnerability still there based in the test for version 13.10 as i said.

Thanks for making it easy. Just two commands, one to see that I need a fix and one to fix it. All done! I’m no linux guru, I just want to run a wordpress server!

I have some droplets with:

Distributor ID: Ubuntu Description: Ubuntu 12.10 Release: 12.10 Codename: quantal

And they don’t update. What i need to do so?

i mean, threre wont be a patch for this (others) version?

For older versions of Ubuntu you can follow the steps here:

http://cloudgames.com/blog/fix-bash-exploit-old-new-releases-ubuntu-apt-get/

You can update the respository to get the latest bash version and then can always set the repository back to the original after updating bash.

Here is what I did for my Ubuntu droplet…

apt-get update && apt-get -y upgrade apt-get install -y bash

seems to have worked

I do an apt-get update and even an apt-get upgrade on my Debian(6) squeeze and it says all packages are up to date so sudo apt-get update && sudo apt-get install --only-upgrade bash does not do anything. Bash is latest version and still not fixed, any other way i can update it?

Great article, well written and easy to follow. Thanks!

Thanks this really useful, i have fixed my bash!!!

If the test on http://shellshock.brandonpotter.com/ is showing no vulnerabilities, but the bash test command does show vulnerabilities, do you think we are safe to wait until the full fix is released?

Thank you,

Hello -

Is it really fixed? :

Still more vulnerabilities in bash? Shellshock becomes whack-a-mole http://arstechnica.com/security/2014/09/still-more-vulnerabilities-in-bash-shellshock-becomes-whack-a-mole/

From the above article I think it is not fixed.

cfg83

Hello -

On my 14.x Ubuntu droplet I am patched up to bash 4.3.11(1)-release

I went here :

https://twitter.com/taviso/status/514887394294652929

And tried this test :

env X='() { (a)=>\' bash -c "echo echo vuln"; [[ "$(cat echo)" == "vuln" ]] && echo "still vulnerable :("

And got this output :

bash: X: line 1: syntax error near unexpected token `='
bash: X: line 1: `'
bash: error importing function definition for `X'
echo vuln
still vulnerable :(

Question: Is the above test legitimate?

cfg83

Thanks a lot, just fixed it on my holaunblocker.com droplet.

For older versions of Ubuntu you can follow the steps here:

http://cloudgames.com/blog/fix-bash-exploit-old-new-releases-ubuntu-apt-get/

You can update the respository to get the latest bash version and then can always set the repository back to the original after updating bash.

Here is what I did for my Ubuntu droplet…

apt-get update && apt-get -y upgrade apt-get install -y bash

seems to have worked

I do an apt-get update and even an apt-get upgrade on my Debian(6) squeeze and it says all packages are up to date so sudo apt-get update && sudo apt-get install --only-upgrade bash does not do anything. Bash is latest version and still not fixed, any other way i can update it?

Great article, well written and easy to follow. Thanks!

Thanks this really useful, i have fixed my bash!!!

If the test on http://shellshock.brandonpotter.com/ is showing no vulnerabilities, but the bash test command does show vulnerabilities, do you think we are safe to wait until the full fix is released?

Thank you,

Hello -

Is it really fixed? :

Still more vulnerabilities in bash? Shellshock becomes whack-a-mole http://arstechnica.com/security/2014/09/still-more-vulnerabilities-in-bash-shellshock-becomes-whack-a-mole/

From the above article I think it is not fixed.

cfg83

Hello -

On my 14.x Ubuntu droplet I am patched up to bash 4.3.11(1)-release

I went here :

https://twitter.com/taviso/status/514887394294652929

And tried this test :

env X='() { (a)=>\' bash -c "echo echo vuln"; [[ "$(cat echo)" == "vuln" ]] && echo "still vulnerable :("

And got this output :

bash: X: line 1: syntax error near unexpected token `='
bash: X: line 1: `'
bash: error importing function definition for `X'
echo vuln
still vulnerable :(

Question: Is the above test legitimate?

cfg83

Thanks a lot, just fixed it on my holaunblocker.com droplet.

Thanks. It worked out perfectly on Ubuntu 14.04 and 12.04.

Does anybody know how to upgrade bash on Debian lenny?

You must use the squeeze-lts repository in order to continue receiving updates to Debian 6 Squeeze

To add this repository, edit /etc/apt/sources.list and add the line

deb http://ftp.us.debian.org/debian squeeze-lts main non-free contrib

To update only bash, after running apt-get update use apt-get install --only-upgrade bash

You all should have been using Zsh instead of Bash in the first place.

We all ought to be using Zsh instead of Bash in the first place.

If you’re using gd’s solution below to build from scratch, change the two loop values from 25 to 26:

for i in $(seq -f “%03g” 0 26); do …

because there is one more patch available, dealing with the latest vulnerability.

Thanks a lot, but is there any opportunity to update my OS X Server?

BTW, here is good HOWTO to protect web applications agains ShellShock, not only servers.

Debian 7 works great!

env VAR=‘() { :;}; echo Bash is vulnerable!’ bash -c “echo Bash Test” Bash is vulnerable! Bash Test So… env VAR=‘() { :;}; echo Bash is vulnerable!’ bash -c “echo Bash Test” Bash Test

Fucking thank you!!!

Great article. Thanks for simplifying it.

Just wanted to say thank you. I am very happy to see that the documentation is growing!

Keep up the excellent work and thank you for your detailed article!

Worked flawlessly on our gitlab

My debian server now passes the above “Check System Vulnerability” test. But I read elsewhere of the test below, which fails: env var='() {(a)=>' bash -c “echo date”; cat echo

Apparently a patched system should not print the date, but my system does. Is this something that requires action in addition to the instructions above?

how to verified account

Thanks for the tutorial, I’m not a regular sysadmin and only fine tune DO droplets when the need arises and then its usually a steep learning curve. I did a backup - the node is 198.199.94.20 Way back I launched a defined DO package for wordpress - my console settings Kernel says “Original Kernel (Ubuntu 12.10 x64 Server vmlinuz-3.5.0.17-generic(25))" I’ve tried to swap the kernel out for one of the options “Ubuntu 13.10 x64 vmlinuz-3.11.0-26-generic” to then do an upgrade but after rebooting it is still at 12.10? I’m wondering why this failed?

I’ve tried using the “do-release-upgrade” - but it comes back with

Your Ubuntu release is not supported anymore. Err Upgrade tool signature 404 Not Found [IP: 91.189.91.14 80] Err Upgrade tool 404 Not Found [IP: 91.189.91.14 80] Fetched 0 B in 0s (0 B/s) WARNING:root:file ‘raring.tar.gz.gpg’ missing Failed to fetch Fetching the upgrade failed. There may be a network problem.

I’ve tried https://www.digitalocean.com/community/questions/update-on-ubuntu-12-10-server-failing-not-found but it aborted and restored back to 12.10

I hear “@manicas” advice that its not recommended to let a server be at 12.10 - but I do have a DO supplied configuration that is at 12.10, and I wonder is there a tutorial for dummies to say how to upgrade it. I have spent a couple of hours trying to stitch together an upgrade. Many thanks.

after i installed the bash update, my php shell_exec command to run pdftk does not work anymre - any ideas what to do?

thanks

I’ve found such tool for vulneratility test: http://www.host-tracker.com/Blog/Shellshock

FYI - I’ve a droplet from a DO supplied application “WordPress on Ubuntu12.10” . The Control Panel Kernel screen says “Orginal Kernel (Ubuntu 12.10 x64 vmlinuz-3.5.0-17-generic(25))” uname –ri lists - 3.5.0-17-generic x86_64 (only one option)

I tried the suggestion in this article, and they didn’t work. I tried a whole bunch of other suggestions that other people have put out there using mirrors supplied by DO - and they didn’t work I tried a Kernel Upgrade - and it turns out that for my DO supplied Ubuntu12.10 distribution it is some strange version (created as a DO application) and it isn’t supported in the Kernel Upgrade - despite there being a lot of options visually available in the Control Panel - Kernel Upgrade. I’ve opened a ticket on the upgrade question, and I’m not getting any reasonable suggestions - it seems DO support is talking Apple Pie - “you need to upgrade” but no reasonable working ways to do it, “Changing the kernel in the control panel does not upgrade the kernel on the droplet.” - with no workable method for what can work.

I’m getting DO advice that aren’t working solutions.

All people running Linux systems whether on local machines or servers were put in panic when a security flaw was discoverd in Bash, the Bash Remote Exploit was nick named as Shellshock.

The vulnerability was exposed in HTTP/CHI scripts and in OpenSSH. It effected nearly all versions of Linux, thankfully there was an update available to secure yourself.

Cloudways was among the first to fix the entire infrastructure and provide extra security to its clients - Here: Bash Remote Exploits

I will have to tell the admin to be careful and follow what the monitoring tool Anturis says and alerts. By the way, are ny monitoring tool at help here?

Thanks Mitchel