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Linux Bash Vulnerability - Test and Solution

Bash Shell Security Vulnerability

There is an important vulnerability in the Linux operating system Bash Shell that has the potential of making your server easily accessible to hackers. By running the test command below, you can see if your bash is vulnerable to exploits. Please run both commands below as root on your server to see if your system is vulnerable.

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1. Log into your server as root
2. Execute the following command:

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

3. If the output is "this is a test", that means that your bash needs to be updated. Please refer to your specific OS below and update your system and bash to latest version.
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and

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1. Log into your server as root
2. Execute the following command:

export dummy='() ; echo "exploited"'

3. Enter the following command afterwards:
bash

4. If the output is "exploited", that means that your bash needs to be updated. Please refer to your specific OS below and update your system and bash to latest version.
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Debian and Ubuntu

1. Log into your server as root
2. Execute the following command:

apt-get update && apt-get -y upgrade

3. Then run the test bash you ran earlier to see if your bash is still vulnerable. If the results are the same run "apt-get install -y bash". If you are still exploited, please reply to this email and our staff will look into it right away.
4. You should see the following command if your server is patched -

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

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Centos

1. Log into your into server as root
2. Execute the following command:

yum clean all && yum update bash

3. Then run the test bash you ran earlier to see if your bash is still vulnerable. If you are still exploited, please reply to this email and our staff will look into it right away
4. You should see the following command if your server is patched -

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

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