There is a one-liner which became very popular after the disclosure of this Shellshock vulnerability. Running the fancy one-liner in your terminal: So, one way of checking is to check your bash version using the following command.
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How to check if your bash is vulnerableīash versions through 4.3 are known to be vulnerable. Why? Because this is not a vulnerability in SSH rather it is the vulnerability in “bash”. Well, you don’t need to worry about this right now, as we will discuss it in detail in a moment.Īs of now, please keep in mind that “our services become vulnerable if we are using any program that uses a vulnerable version of bash as an interpreter and if the attacker is able to control the value of an environment variable that is being passed to bash”. You may be vulnerable if you have implemented “authorization_keys” for your clients with some specific requirements like “force command” execution before the user executes the commands. There are a few limitations in order to exploit this, as explained below. Your SSH doesn’t really need to be exploited if you are using OpenSSH as an SSH Server as well as bash as your default shell. I will make things clear using SSH as an example. If you have read some news about Shellshock on the Internet, you might have heard about vulnerable targets as follows: Apache mod-cgi, SSH, DHCP, etc. This will also help us in building a lab to demonstrate how to exploit this vulnerability.
Before understanding how to exploit this Shellshock vulnerability, we need to understand the potential targets that are vulnerable to Shellshock. This is the most important piece of this article. Shellshock is a vulnerability in GNU Bourne Again Shell (BASH), which allows an attacker to run arbitrary commands using specially crafted environment variables. Then it walks readers through the step-by-step procedure of how to set up their own lab to demonstrate a Shellshock vulnerability along with the exploitation part. This article first gives you the internal details of the vulnerability. After “Heartbleed”, it is the most widely spread word in the recent past. Shellshock is now one of the buzzwords in the security community.