[ale] Is Promiscuous Sniffing just not so much Fun anymore? (mostly on-topic)
Neal Rhodes
neal at mnopltd.com
Tue Dec 10 22:19:34 EST 2013
Thanks to all for the answers.
In our case, switch from http to https is trivial change. No
application code change needed. I was trying to figure out if it
bought us anything.
I'm also thinking on
- establishing IP address checking of caller and reject if not on
pre-existing list;
- access code in band; I was originally thinking this was stupid, but if
packets are encrypted, perhaps not quite stupid. One more layer of
difficulty, although as you note, it would require compromising the
weakest host on the data center LAN before you could even attempt to
sniff.
The target, beyond auditors, is to make it difficult for moderate
quality rogue who somehow gets onto the LAN, in spite of having no Wifi,
and even the LAN switches won't accept an arbitrary MAC address getting
plugged in.
On Tue, 2013-12-10 at 20:09 -0500, dev null oh two wrote:
> what if I compromised a host on the same switch as the servers and
> used ARP spoofing or overflowed the CAM table, or any other number of
> L2 attacks to then sniff your unencrypted data?
>
> I have compromised many lower "importance" hosts and then pivoted
> inward and pcapped $sensitive_data because admins don't understand the
> idea of layered defense.
>
> PCI is generally bullshit, but on this point, your auditor is right.
>
> and if you're going to implement TLS between the servers, please, use
> PFS.
>
>
> On 12/10/2013 7:45 PM, Brian Mathis wrote:
>
> > If the local switch was compromised and placed into monitor mode,
> > then a 3rd party could sniff the traffic, but now you're talking
> > some really specific case. It's generally considered secure to have
> > one server talk to another over a local switch, otherwise things
> > like NFS and databases would be a huge pain, if not impossible to
> > use.
> >
> >
> >
> > However, which do you consider more of a threat? The overhead of
> > switching to HTTPS, or an auditor who fails you on an audit? Maybe
> > you would pick the former, but I'm sure your business would pick the
> > latter. Keeping auditors happy is just as important as "real" work.
> >
> >
> >
> >
> > ❧ Brian Mathis
> >
> >
> >
> >
> > On Tue, Dec 10, 2013 at 5:42 PM, Neal Rhodes <neal at mnopltd.com>
> > wrote:
> >
> > I hear that. But two servers, same rack, plugged into the
> > same switch, on the same LAN, will not hit their gateway
> > router - they will ARP to find each other, and talk through
> > the switch, and you ain't gonna see any of that, even if you
> > managed to plug into the data center switch. Correct?
> >
> > We're playing a little devil's advocate here, trying to
> > decide if we're looking at securing against a realistic
> > threat or just keeping the auditors happy.
> >
> >
> > On Tue, 2013-12-10 at 17:02 -0500, JD wrote:
> >
> > > If 2 locations are connected through public internet, don't trust it. There are
> > > routing attacks which have been known for years and I suspect any 2 sites using
> > > HTTP or HTTPS connections in that way will be unlikely to be monitoring network
> > > performance at much detail.
> > >
> > > Servers should be on a different subnet and fire walled from desktops even in
> > > the same location.
> > >
> > > Can't recall where I saw a recent article about this, but routing has both
> > > accidentally and with clear purpose caused traffic to be sent very far away from
> > > expected places. Recall when all youtube traffic was sent through Pakistan
> > > "accidentally"? I am positive that could be done between two corporate locations
> > > using the internet for connections too.
> > >
> > > IPSec. Not sure I'd trust anything less.
> > >
> > > On 12/10/2013 02:08 PM, Neal Rhodes wrote:
> > > > So, picture two servers which talk to each other within a corporate LAN/WAN in a
> > > > data center, and worker bees in an office location elsewhere in the same city,
> > > > who only have hard-wired LAN access, and assume they have IP connectivity to the
> > > > data center.
> > > >
> > > > And picture that these two servers have an unsecured http protocol they talk over.
> > > >
> > > > And picture a worker bee with too much time on their hands and the intent to
> > > > hijack this.
> > > >
> > > > If said worker bee managed to get WireShark or similar installed on their
> > > > workstation, they could sniff whatever that hard Cat5 cable can see. Which,
> > > > assuming it is connected to a switch, not an old-fashioned hub, is pretty much
> > > > zilch. Basically their own traffic.
> > > >
> > > > They can't see most traffic to/from the guy in the next cubicle to the servers,
> > > > because the switch doesn't normally let them see it. For performance reasons,
> > > > it isolates each LAN port. They can't see any of the server-server packets,
> > > > because the two routers in between behave like switches, not hubs, and don't
> > > > route local server-server traffic.
> > > >
> > > > So, assuming that Wifi is not available, it seems like the LAN sniffer attack
> > > > vector based on seeing what is happening is pretty much moot. That is not to
> > > > say that actively probing isn't rewarding.
> > > >
> > > > Let's take it one step farther: presume that it is trivial for these two servers
> > > > to switch from talking http:80 to each other and start talking https:443 to each
> > > > other. From the perspective above, this is a negligible practical
> > > > improvement. It only gets interesting if we imagine someone able to get onto
> > > > the local LAN in the data center. But even then, presuming that is also a
> > > > switch, they ain't gonna see spit.
> > > >
> > > > Let's take it one step farther: assume that they could in fact compromise the
> > > > data center switch, and capture a pile of the https traffic between servers.
> > > > Would we logically assume that given today's technology that they could manage
> > > > to decrypt it with enough CPU and time?
> > > >
> > > > Thoughts?
> > > >
> > > > Neal Rhodes
> > > > MNOP Ltd
> > > >
> > > >
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