Techie Tuesday: Defending against the “BASH Shell Bug” so as not to cause “Shellshock”

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On September 24, 2014 the news reported that there was a major issue with something called the BASH shell, this was Unix/Linux’s first major Vulnerability.

For those who don’t talk techie, the “shell” is a program written for the Unix/Linux operating systems to allow logged in users to communicate with the Unix/Linux server. The first shell was developed back in 1977, by Stephen Bourne at Bell Labs was called, not surprisingly, The Bourne shell. In 1992, Chet Ramey, Brian Fox, and others further developed the Bourne shell for the Linux operating system and called it the Bourne again shell, i.e.; the BASH Shell.

As the news reported, there has been a problem discovered within the BASH shell program where under certain circumstances you can access the shell without supplying a user password. If root, the administrator for a Unix/Linux server, is using the BASH shell, this means someone could break in and run commands as root. This is a major issue within the Linux world because roots default shell is the BASH shell.

What you need to remember is although this bug is serious, if you have a firewall protecting your servers and appliances, the attackers will not have access to the effected hardware and software to try and break in.

Now, this information may make it seem that if you are not running Linux servers you have no worries.  That is not true. The problem is most people don’t know what operating system is running many of the appliances in their environment. Linux is used by many companies to run their appliances as it is one of the more reliable, powerful, and flexible and, not withstanding this article, operating systems least effected by viruses out there today.

A complete list of effected hardware and software from IBM can be accessed by clicking here, but for example HMC’s, V7000 and SAN Switches are just a few of the hardware components affected. Of course, UNIX systems of any flavor, including AIX, running the BASH shell are all affected.

Kevin Young – Senior Technical Specialist


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