RE: Wired captive portal pen-test

["Sergio Castro" <sergio.castro () unicin net>]

What I mean is that if he's not seeing ARP requests, it means there's a
switch-router there, and not a hub.

As to MITM, if the switch-router is FULLY secured, it is correct, you cannot
launch such attack. But if it has a standard, medium security configuration,
such attacks are possible; I do them all the time. But that's why I said
that he MAY be able to do it, not that he CAN do it :)

Regards,

- Sergio 

-----Mensaje original-----
De: listbounce () securityfocus com [mailto:listbounce () securityfocus com] En
nombre de "Jos?é M. Palazón Romero"
Enviado el: Miércoles, 16 de Julio de 2008 03:28 a.m.
CC: pen-test () securityfocus com
Asunto: Re: Wired captive portal pen-test

Sergio Castro escribió:
> So yes, if you only see broadcast ARP requests from the router, the 
> switch is very likely securely configured.

This is incorrect, Sergio. ARP replies are not broadcast, so it's perfectly
ok that he doesn't see them.

> Did you try using Cain? You may be able to do ARP poisoning with it 
> and intercept traffic between the router and IPs in your same subdomain.

If the switch were secured, then this wouldn't work either. Not even an ARP
spoofing would work. The only option would be to find a flaw in the switch
firmware or to trick it in such a way that, as most switches do, that it
doesn't know how to behave anymore, and it starts acting as a hub. But it's
unlikely that you find this in any modern switch. Have you tried to atack
the switch itself? Try the firsts and the lasts IPs in your network. If the
switch is advanced enough to filter that way, then it has a way to setup
that, and probably that's a web interface. Try also uPNP. It's no
authenticated, so if it's enabled, is your lucky day.

Anyway, I still think they are probably not filtering at layer 2.

Palako

> - Sergio
>
> -----Mensaje original-----
> De: Roman Medina-Heigl Hernandez [mailto:roman () rs-labs com] Enviado 
> el: Lunes, 14 de Julio de 2008 02:34 p.m.
> Para: Sergio Castro
> CC: pen-test () securityfocus com
> Asunto: Re: Wired captive portal pen-test
>
> Sergio Castro escribió:
> > I've done similar voipsec audits at hotels. The hotel is very likely 
> > using a switch-router (and very likely VLANs) so you will not be able 
> > to see any other IPs on the network. What is your sniffer showing?
>
> I saw ARP requests coming from the router and asking for the MAC of 
> several other IPs of the same segment where my laptop was connected 
> (in my case, 192.168.9.x). I didn't catch any ARP responses...
>
> Another probe I did was walking to a "public computer" in the hotel 
> (some kind of internet-kiosk) and get the IP. The IP was in the same 
> 192.168.9.x range. I didn't have time to get its MAC and try to 
> configure my laptop's NIC with that MAC (although the switch should
probably stop that...
> shouldn't it?).
>
> > Another possible attack vector you may use is their IP phones. If the 
> > room has an IP phone, try connecting your laptop to the phone's RJ45 
> > and do a packet sniff. I've been able to access entire corporate LANs
> doing this.
>
> I didn't have a look at this... although I'd guess it was rj-11... 
> Next time I'll check it! :)


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