RE: [fw-wiz] PIX -> ISA -> OWA Configuration

From: Paul Melson (psmelson_at_comcast.net)
Date: 05/03/05

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    To: "'Jason Gomes'" <greyline@phreaker.net>
    Date: Tue, 3 May 2005 09:06:34 -0400
    
    

    Definitely. In #1, if the ISA server is configured via the OWA publishing
    wizard, it will create ACL's that prevent requests that don't match
    /exchange/* from being passed to IIS. You can also run urlscan at the ISA
    server (though it requires some tweaking to keep from breaking some of OWA's
    functionality).

    In #2, the same thing applies, but should the ISA server be compromised say
    via buffer overflow, then there is no protection for the internal AD domain,
    since those holes must be punched straight through the firewall (and they
    are BIG holes).

    PaulM

    -----Original Message-----
    Subject: Re: [fw-wiz] PIX -> ISA -> OWA Configuration

    Definitely? Under #1 it seems like something as simple as a directory
    traversal attack against IIS/OWA that manages to get through ISA leaves your
    entire internal network exposed. Under #2 it appears to me that an attacker
    would need at the very least a second exploit to gain further access to the
    trusted network.

    > -----Original Message-----
    > What is the preferred placement for a OWA front-end server given these
    > two possible network configurations and why?
    >
    > 1) [Internet] <==> [PIX Firewall] <==> [ISA Proxy] <==> [PIX Firewall]
    > <==> [OWA] <==> [Internal Net w/Exchange Svr]
    >
    > 2) [Internet] <==> [PIX Firewall] <==> [ISA Proxy] <==> [OWA] <==>
    > [PIX Firewall] <==> [Internal Net w/Exchange Svr]

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