Re: Re: Gaim festival plugin exploit

[Dale Harris <rodmur () maybe org>]

On Thu, Oct 23, 2003 at 02:52:36PM -0400, Scott Phelps / Dreamwright Studios elucidated:
> This is great, somebody is arguing Perl syntax with the guy who co-wrote the
> llama book.

Probably an honest mistake.

> -----Original Message-----
> From: full-disclosure-admin () lists netsys com
> [mailto:full-disclosure-admin () lists netsys com] On Behalf Of Randal L.
> Schwartz
> Sent: Thursday, October 23, 2003 11:04 AM
> To: Brian Hatch
> Cc: HCTITS Security Division; bugtraq () securityfocus com;
> full-disclosure () lists netsys com
> Subject: Re: [Full-disclosure] Re: Gaim festival plugin exploit
>
> > > > > > "Brian" == Brian Hatch <full-disclosure () ifokr org> writes:
>
> > > > > system("echo \"$string\" | /usr/bin/festival --tts");
> > >
> > > Replace this with
> > >
> > > open FEST, "|/usr/bin/festival --tts";
> > > print FEST $string, "\n";
> > > close FEST;
> > >
> > > No shells involved.  Only DOS exploits and maybe the usual
> > > C-language overflows in festival itself.
>
> Brian> Well, no, that open does invoke a shell, albeit one with
> Brian> no user input.
>
> Excuse me.  No it doesn't.  I dare you to watch a trace of that
> program and tell me if EVER a /bin/sh is invoked.  It doesn't.  It
> forks, and calls festival directly.  Just a child.  No grandchild.  No
> chance for a shell interpretation.

So let me guess  open FEST "|..." uses popen(), right?  Therefore a
shell is invoked, and it won't show up on strace, because popen() is too
high level for that kind of trace.


Dale

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