On 26 September 2014 16:25, Doug Newgard email@example.com wrote:
On 2014-09-26 09:15, lolilolicon wrote:
On Fri, Sep 26, 2014 at 9:50 PM, Doug Newgard firstname.lastname@example.org wrote:
The problem is on many systems /bin/sh is linked to bash -- which is why
this bug is so widespread / severe. /bin/sh is "the single biggest UNIX loophole", so let's make it a bit smaller by switching it to something minimal, such as dash.
Why? Why is that the problem? What attack vector is available because of this? Give me specifics, not theoretical, non-existent examples.
Because the vulnerable systems do not call bash by name, they call /bin/sh. And they are vulnerable only because /bin/sh is linked to bash.
Wrong, they DO call bash by name. The main issues are with ssh, which uses the user's specified interactive shell, and with Apache's mod_cgi and mod_cgid, which do call bash. Again, stop providing non-existent FUD and give real-world examples of where having /bin/sh linked to something else would have mitigated this.
Some programs may call bash by name, but many will just use system() and get bash without asking for it.
From man 3 system:
The system() library function uses fork(2) to create a child process that
executes the shell command specified in command using execl(3) as follows: execl("/bin/sh", "sh", "-c", command, (char *) 0);