[VOIPSEC] Actual Attacks

[Thomas Howe]

Hi all -

Excellent exchange.

One important thing about endpoint vs. SBC security that I didn't see 
mentioned here, and that's money.  The real big money to be made for 
hackers in VoIP is in extortion, not in the petty cyber-vandelism of 
VoIP script kiddies.  In order to make money at extortion, there's got 
to be a whole bunch of victim's money at risk.  At the residence, or 
even at the small to medium enterprise, there's just simply not enough 
money at stake to make it worthwhile.  However, if you are talking about 
a service provider of any appreciable size, how much would they pay not 
to be taken out of service for a day or two?  DDOS is not a good thing 
for them, and it's really easy to get a 10,000 element botnet up and 
going.  If anyone disagrees with this pessimistic view of the future, I 
will only point to the current problems suffered by online gambling 
sites, and mention that their effective revenue is one-tenth that of a 
mid-level carrier.  Therefore, because the money is there, and that's 
where the real hackers go, SBC and service provider firewalls are the 
places we need to concentrate.

Just my opinion.
Tom


Brian Rosen wrote on 2/24/2005, 1:11 PM:

 > So, before the specifics, an opportunity to vent:
 > <rant>
 > I've been involved in work that seeks to allow distributed teams of
 > people
 > to work cooperatively with one another while separated by distance.
 > My team
 > has produced tools which are quite effective.  One of the interesting
 > aspects of "effective" is how you define it.  Our definition is "you
 > behave
 > the same using the tool as you do when you are in the same room with your
 > team".  We have also sought to use tools produced by others to expand our
 > own work.
 >
 > In the 6 or 8 years I've been working on this problem, we have had
 > exactly
 > two sustained, relatively unsolvable-by-us problems.  One is the cost of
 > bandwidth.  It was dropping like a stone, but it hasn't been lately.
 >
 > The other is the "security teams" in the enterprises where we worked
 > (sorry
 > Britt).
 >
 > These guys have stopped us cold.  They simply will not allow us to deploy
 > the tools.
 >
 > Let me get into a specific.  One of the most effective tools out there is
 > the applications sharing tool in Netmeeting.  It's been out,
 > available, and
 > free for 10 years.  Yet, today, 90% of the deployed firewalls stop it.
 >
 > So, what have we done?  I'll tell you what we did; we changed the
 > protocol
 > to HTTP, that's what we did.  See WebEx.
 >
 > WebEx is not quite as good as Netmeeting, and it costs a heck of a lot
 > more,
 > but it goes through the firewall because it runs on HTTP.
 >
 > Is that the right answer? NO! It is the wrong answer.  HTTP is not an
 > appropriate protocol for real time application sharing.  The result of
 > the
 > stupidity of not allowing dynamic UDP ports running T.120 in any
 > reasonable
 > way is to force people to get on planes and fly to meetings rather
 > than sit
 > in their office and have the meeting distributed (or pay through the
 > nose to
 > make an end-to-end problem a service provider business opportunity while
 > bypassing the firewall).
 >
 > I'll go farther.  Firewalls are a very bad idea.  They have become a
 > crutch
 > that has two significant, unfixable problems:
 >     1. It breaks end to end connectivity that is the basis of the
 > Internet
 >     2. It provides a convenient short cut to avoid fixing problems
 > The latter is the real issue.  The former is just a consequence.  By
 > using
 > the firewall to stop known attacks, you push off the need to fix the
 > endpoints.  That's a bad approach because there is always a back door.
 > WebEx is an example of a back door.  IP over HTTP is available.
 >
 > The right way is to fix the endpoints.  We're dealing with this in IE and
 > Outlook and ..., because the firewalls don't stop the problems.  We
 > should
 > deal with it in all the applications.  I know it sounds harder, but
 > actually, these days, it's not really.  We should give up on walled
 > gardens.
 > It's getting too easy to breach the walls.  We should deploy systems that
 > are secure end to end (although getting that with a hop by hop
 > mechanism is
 > more likely).
 >
 > The security teams must hate the fact that VoIP is a reality in most
 > enterprises that are upgrading their phone service.  They haven't
 > gotten to
 > the real problem yet, but they are about to.  VoIP peering is coming on
 > fast.  That means instead of just having to allow VoIP within the
 > enterprise, they have to allow it between enterprises.  And that
 > traffic is
 > all going to be SIP.  SIP is the interchange protocol for domains that do
 > not have bilateral arrangements.  All carrier peering is going to
 > SIP.  They
 > may accept H.323 at the boundary (SBC), so the enterprise could
 > maintain all
 > H.323 interfaces, if they are content to pay carriers to make all their
 > interconnections.  But, like Email, why would they?  If you can make a
 > SIP
 > call over the Internet, and you can receive one, why would you pay a
 > carrier
 > to connect you to someone else who can do that?
 >
 > </rant>
 >
 > And now we return to our regularly scheduled program -- comments inline
 >
 > > -----Original Message-----
 > > From: Christopher A. Martin [mailto:chris at sip1.com]
 > > Sent: Wednesday, February 23, 2005 11:03 PM
 > > To: 'Brian Rosen'; 'Simon Horne'; voipsec at voipsa.org
 > > Subject: RE: [VOIPSEC] Actual Attacks
 > >
 > > I would like clarification regarding your comment below:
 > >
 > > "> SBCs and firewalls are very unfriendly to any signaling security,
 > > because
 > > > they want to peer into the signaling, and sometimes alter it.  They
 > > could
 > > > be
 > > > more visible in the process; for example, a firewall or SBC could
 > be a
 > > > real
 > > > SIP proxy server, in the routing path, and thus be a hop in the TLS
 > > path."
 > >
 > > The fact that an organization or individual places the trust on SIP
 > > endpoints, in this case, to basically bypass security measures
 > (which you
 > > stated are unfriendly to signaling security) is ludicrous to me.
 > Maybe so, but if I got a sips: call from a domain who's cert I was
 > reasonably sure of, I think I'm a heck of a lot better off than getting a
 > sip call that passed someone's firewall.
 >
 > Firewalls (and SBCs) are unable to do anything really useful with
 > respect to
 > creating SECURE connections.  They hurt.  They can stop some kinds of
 > problems, but secure connections from an open port are probably a heck
 > of a
 > lot more useful than insecure connections from a firewalled port.
 >
 > YMMV.
 >
 > >
 > > Firewalls and border controllers are not merely in place to facilitate
 > > VoIP,
 > > :) well at least not the former. They are in place to protect the
 > > infrastructure from unauthorized use of resources at various levels,
 > > whether
 > > it is a home user, enterprise application, or carrier service. But they
 > > are
 > > not the silver bullet either.
 > Well, as above, I think they are an ill-conceived crutch.  They are there
 > however.  Denying reality rarely gets you anywhere.  If they are
 > there, then
 > they either have to do one of two things:
 > 1. Be an active participant in a TLS hop-by-hop signaling path, so
 > that they
 > can look at the signaling and do their thing with it.  This breaks if
 > S/MIME
 > is used to protect the end-to-end stuff, but it's better than nothing.
 > 2. Pass all TLS protected signaling and sRTP protected media through
 > with no
 > inspection.
 >
 > There is a third option, see below.
 >
 >
 > >
 > > Firewalls are becoming more intelligent as they evolve to meet the
 > needs
 > > of
 > > these new protocols and applications and because they have to in
 > order to
 > > provide the protection that they were originally intended for. They
 > are a
 > > fact of life that will not go away. IDS's and IPS's are also going
 > to have
 > > to evolve in this direction too.
 > Actually, what I see happening in the wild is that people are
 > deploying SBCs
 > in parallel with the firewalls, because the firewalls are not evolving
 > fast
 > enough to keep up.  I don't like most SBCs either, but they are being
 > deployed.  I don't see many firewalls that have full SIP support being
 > deployed.
 >
 > But to reiterate, neither of them correctly deals with secure
 > connections,
 > and I have big problems with that.
 >
 > >
 > > SIP and other peer to peer protocols like it pose a very real threat to
 > > these environments. The very fact that we developed the enablement of
 > > these
 > > protocols through these security mechanisms means that the dynamic
 > > pinholes,
 > > port redirections, and what have you, are now fully authorized
 > conduits of
 > > whatever mischief can be thought up unless the security mechanism can
 > > "peer"
 > > into the signaling and/or media to determine authorization and
 > > authentication is not being attacked.
 > Nope. The idea that you have to "peer" into the signaling is the wrong
 > approach.  You make the endpoints secure, and depend on them.  You can
 > never
 > make the walled garden secure.
 >
 > The firewall vendors have not been very supportive of the "midcom" stuff
 > that seeks to have intelligent signaling devices be able to tell them
 > how to
 > open the pinhole.  Probably an economic issue, as well as a control-freak
 > kind of thing.  Reality is that there is no other way to correctly
 > determine
 > how to open the pinhole.
 >
 > I'm not a fan of pin hole firewalls, but if you want to do it, do it
 > right.
 > That means having the endpoint tell you which ports it needs.  There
 > is no
 > other way, because the intermediaries can't look into S/MIME protected
 > SDP.
 > Telling me not to protect my signaling with S/MIME is an unacceptable
 > answer.
 >
 >
 > >
 > > What we have to do is determine how to find the middle ground to an
 > > acceptable risk and develop this so that there can be confidence in
 > using
 > > the applications derived from it.
 > Sure, but that means the firewall is active, and not passive, if it is
 > there
 > at all.
 >
 > >
 > > Signaling security should also be designed with these things in
 > mind, not
 > > just the other way around...infrastructures are built of many
 > components,
 > > some are standards based, and some are for survival. You have to
 > look at
 > > the
 > > whole picture.
 > Well, in some sense I agree with you.  For some time the signaling
 > protocol
 > folks have been wishing firewalls and NATs would go away, and designing
 > systems that assume they are not there.
 >
 > But then the firewall guys have not been exactly cooperative about
 > making it
 > possible to do the right thing, as above.  Endpoint signaling of pinholes
 > for example.
 >
 >
 > Brian
 >
 >
 >
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