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Bash Vulnerability
Posted by Chris -'- Ahosting Support Team on 25 September 2014 04:45 PM

Critical Bash updates
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There is a critical CVE vulnerability affecting all versions of the bash package. This vulnerability could allow for arbitrary code execution. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue. An attacker can provide specially-crafted environment variables containing arbitrary commands that will be executed on vulnerable systems under certain conditions.

You may find the details of the vulnerability from the following URL's:

http://centosnow.blogspot.com/2014/09/critical-bash-updates-for-centos-5.html

https://access.redhat.com/articles/1200223

http://askubuntu.com/questions/528101/what-is-the-cve-2014-6271-bash-vulnerability-and-how-do-i-fix-it

To test if your version of Bash is vulnerable to this issue, run the following command:

For Centos Server
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To test if your version of Bash is vulnerable to this issue, run the following command:

$ env x='() { :;}; echo vulnerable'  bash -c "echo this is a test"

If the output of the above command looks as follows, then the bash is vulnerable. Please run the command (yum update bash)

vulnerable
this is a test

you are using a vulnerable version of Bash. The patch used to fix this issue ensures that no code is allowed after the end of a Bash function. Thus, if you run the above example with the patched version of Bash, you should get an output similar to:

$ env x='() { :;}; echo vulnerable'  bash -c "echo this is a test"
bash: warning: x: ignoring function definition attempt
bash: error importing function definition for `x'
this is a test
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For Ubuntu Server
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The fixed versions are 4.3-7ubuntu1.1, 4.2-2ubuntu2.2, and 4.1-2ubuntu3.1. You can perform this update using apt-get.

First, check your package version:

dpkg -s bash | grep Version

This will look up info on your bash package, and filter the output to only show you the version.

For example, I see:

wlan1-loopback% dpkg -s bash | grep Version
Version: 4.3-7ubuntu1.1

and can determine that I am not vulnerable.

If you are vulnerable, you should first grab the newest package lists:

sudo apt-get update && sudo apt-get install bash

The first step makes sure that you have the newest package list that includes the fixed version, and the second command installs the newest (fixed) version of bash.

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We will check this and will do the needful for the server's for which root access is allowed for us. For the server's which we do not
have root access or updated passwords in billing, please perform the above mentioned patching steps.

If you want us to perform this, kindly provide us the root access to server.

Thank you very much!

If you have any questions, please don't hesitate to open a ticket with our helpdesk , we will be happy to assist you.


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