My buddy Aamir Lakhani posted about the recent Shellshock / Bash bug based on his research. Its a fantastic post and original is located HERE.
Security researcher, Stephane Schazelas found a major vulnerability that allows attackers to execute and run code in bash shell.
A shell is found on most UNIX, Linux, and Mac operating systems. Users interact it with it through the terminal program. It is the place to input and run commands for the operating system, as well as accept basic programming for the system. In other words, it is the command line. It is used for management, administrative, and productivity purposes.
Bash is the shell, or command language interpreter, for the GNU operating system. The name is an acronym for the ‘Bourne-Again SHell’, a pun on Stephen Bourne, the author of the direct ancestor of the current Unix shell sh, which appeared in the Seventh Edition Bell Labs Research version of Unix.