[ale] Is Promiscuous Sniffing just not so much Fun anymore? (mostly on-topic)

[Brian Mathis]

On Tue, Dec 10, 2013 at 2:08 PM, Neal Rhodes <neal at mnopltd.com> 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
>


You'd be surprised at how much stuff comes through a switch as broadcast
traffic, and there's always tools like ettercap which can overflow the
switch MAC address table, forcing it to revert to "hub" mode (in addition
to other MITM attacks).

It is not feasible to decrypt https traffic unless you have access to the
private keys, which are hopefully stored securely on the remote web server
somewhere. Or you can perform a man-in-the-middle attack where the user
accepts the invalid certificate (which is entirely possible).  Even the NSA
needs the private keys, which is what those secret court orders are all
about.

The "enough CPU and time" part of your question is not really relevant.
The answer to that question is "yes", because it dismisses the two most
important constraints in evaluating any cryptography.  CPU and time are THE
most important constraints, as anything given enough time can be broken,
but we're talking on the order of billions of years.  The most important
qualifier there is "reasonable within your lifetime".


❧ Brian Mathis
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