Re: shell script cgi

> thought the wrong way in my last message.
>
> Try the following string for $HTTP_USER_AGENT:

The HTTP_USER_AGENT string is set by Apache (etc) as an environment variable. Let's make the unradical assumption that your browser is not a shell script, and thus is setting it correctly without any shell expansion problems possible. So HTTP_USER_AGENT is set to

        `cat /etc/passwd`

To emulate this, let's set it ourselves in a normal shell:

	bash$ export VAR='`cat /etc/passwd`'
	bash$ echo $VAR
	`cat /etc/passwd`

I use the single quotes here to make sure no expansion tricks are possible, which is how your web browser will work. The var is set exactly. Excellent. Can we abuse it?

	bash$ echo $VAR
	`cat /etc/passwd`
	bash$ echo "$VAR"
	`cat /etc/passwd`

Nope. How 'bout if we have:

	bash$ export VAR='blahblahblah *'
	bash$ echo $VAR
	blahblahblah file1.cgi file2.cgi file3.cgi
	bash$ echo "$VAR"
	blahblahblah *

Do you need help?

In addition to our free technical library, Pantek provides professional IT services to companies who utilize Open Source software: Learn more about Pantek's Technical Support offerings Place an order for 24/7/365 Technical Support here Learn more about Pantek, who we are, and what we do Chat with a Live Operator Related securityfocus.com Links bugtraq certification focus-bsd focus-ids focus-ih focus-linux focus-ms focus-sun focus-unix-other focus-virus forensics incidents libnet linux-secnews ms-secnews pen-test secpapers secprog sectools secureshell security-basics securityjobs sf-news vuln-dev webappsec Request more information about Pantek

See that with no quotes you can get a file listing through shell expansion.

--
Brian Hatch                  I used to be a lumberjack,
   Systems and                but I just couldn't hack
   Security Engineer          it, so they gave me the ax.
http://www.ifokr.org/bri/

Every message PGP signed