Who would grant `sudo` privileges to `www-data` without asking for a password? That's just asking for a bad time.

you could prolly get around that

if their httpd.conf has incorrect privs set, you could run a script that changes the "user to run as" to root, then set up a script that would run on next reboot to apt-get upgrade and remove the root privs config line. you'd have to wait for the server to go down or reboot however long in the future, but hey it would work.

The same people who write CGI applications in bash?

Your CGI application does not need to be written in bash for you to be vulnerable. If at any point your non-bash CGI program (and this includes PHP, even with mod_php, since it sets the same environment variables), or one of its descendant processes, executes a bash script, you can be exploited.

This is especially bad on systems where /bin/sh is /bin/bash, since /bin/sh gets invoked implicitly by system(3). So you could have a non-bash CGI program invoking a non-bash program using system(3) and you can be exploited.

According to https://access.redhat.com/articles/1200223, mod_php is not vulnerable.

You're right; thanks! I saw the HTTP_* variables in phpinfo() and assumed they'd be passed on to children through system(), but they actually aren't. In fact the only environment variables passed through look pretty innocuous.

I didn't say it required it. I simply pointed out (albeit sarcastically) that CGI scripts do get written in bash, and people often often make use of sudo within them. I've seen such a beast in production at multiple companies.

The amusing up/down vote war I am watching on my karma gives me hope that at least 50% of HN got it...

Does this qualify as white-hat or grey-hat hacking? Does the doing only good outweigh the bad of modifying someone else's system?

It's a long-running debate in the security community, almost as big as full-vs-responsible disclosure.

On the pro side, it's better than you get patched than stay vulnerable and fall into someone else's zombie list.

On the anti side, you don't know what you are messing with and could break things, oh, and it's illegal and you can go to jail.

On the anti-anti side, if you can't be held responsible to patch your machines, don't complain when someone else does it for you.

That's the barest summary.

Relevant helpful viruses:

https://en.wikipedia.org/wiki/Welchia http://virus.wikidot.com/codered (CodeGreen)