Great Circle Associates Firewalls
(September 1995)
 

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Subject: Re: Secure version of Sendmail
From: mdr @ vodka . sse . att . com
Date: Thu, 14 Sep 1995 15:39:46 -0400 (EDT)
To: peter @ nmti . com (Peter da Silva)
Cc: firewalls @ greatcircle . com
In-reply-to: <9509141616 . AA24527 @ sonic . nmti . com . nmti . com> from "Peter da Silva" at Sep 14, 95 11:16:27 am

> 
> > True enough. The point is, you have to identify and exploit
> > appropriate holes in both sendmail and in the nonbypassible access
> > control mechanism of the OS. A properly designed mechanism is going to
> > present a different kind of penetration problem.
> 
> The point is that if you have a class B O/S you're more likely to skimp
> on the application level stuff. If you get both, that's great, but you
> usually only get one.

Yea right, I'm gonna go to the trouble of finding and administering a 
class B OS but I don't care enough about security to fix the application 
level bugs.  The class B stuff protects the OS from the apps, but it
doesn't ensure that the apps themselves work properly.   However, it
can monitor some aspects of the applications behavior.

> 
> I just found another:
> 
> 	sprintf(txt, "sendmail -f %s %s < %s",
> 		user_provided_string, server_provided_string, tempname);
> 
> in a web server CGI script.
> 
> Just pop "; mail phreak < /etc/passwd" in as your address...
> 

And you don't see the need for a secure OS undeneath your CGI
scripts?   Amazing.  

You should run it in a chroot jail as a bare minimum.  A C2 or higher
OS would be able to spot this kind of bug by monitoring what the CGI
script does via the audit trail.


Mark Riggins
Secure Systems Engineering
AT&T Bell Labs



Follow-Ups:
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Next: I wish Java would go away...
From: Scott Barman <scott @ Disclosure . COM>
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