Shellshock: No, it IS a bash bug

Posted by Jim Jagielski on Monday, September 29. 2014 in Open Source

Reading over, I am surprised just how wrong the entire post is.

The gist of the post is that the Shellshock bug is not bash's fault, but rather, in this argument, the fault of Apache and other facing programs in not "sanitizing" the environment before it gets into bash's hands.

Sweet Sassy Molassy! What kind of horse-sh*t is that?

As "proof" of this argument, pjb uses the tired old excuse: "It's not a bug, it's a feature", noting that bash's execution of commands "hidden" in environment variables is documented; But then we get the best line of all:

The implementation detail of using an environment variable whose value starts with "() {" and which may contain further commands after the function definition is not documented, but could still be considered a feature 

As far as outlandish statements, this one takes the cake. Somehow, Apache and other programs should sanitize magical, undocumented features and their failure to do so is the problem, not that this magic is undocumented as well as fraught with issues in and of itself.

Let's recall that if any other Bourne-type shell, or, in fact, any real POSIX-compliant shell (which bash claims to be), were being used in the exact situation that bash was being used, there would be no vulnerability. None. Nada. Zero. Replace with ksh, zsh, dash, ... and you'd be perfectly fine. No vulnerability and CGI would work just fine. And also let's recall, again focusing on Apache (and all web servers, in fact; It's not just Apache is affected by this vulnerability but any web server, such as nginx, etc...), the CGI specification specifically makes it clear that environment variables are exactly where the parameters of the client's request lives.

Also, let's consider this: A shell is where the unwashed public interfaces with the OS. If there is ANY place where you don't want undocumented magic, especially in executing random code in an undocumented fashion, it AIN'T the shell. And finally, the default shell is also run by the start-up scripts themselves, again meaning that you want that shell to have as few undocumented bugs... *cough* *cough*, sorry "features" as possible, and certainly not one's that could possible run things behind your back.

Yes, this bug, this vulnerability is certainly bash's, no doubt at all. But it also goes without saying that if bash was not the default shell (/bin/sh) on Linux and OSX, that this would have been a weaker vulnerability. Maybe that was, and is, the main takeaway here. Maybe it is time for the default shell on Linux to "return" to the old Bourne shell or, at least, dash.


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