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[asterisk-users] is encrypted iax safe and secure?

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Claudio.Cavalera at it...
Guest

Posted: Tue Feb 05, 2008 10:22 am Post subject: [asterisk-users] is encrypted iax safe and secure?

Hello, I'm doing some research concerning iax encryption, I haven't find any clients (softphones or hardphones) which implement so I have not tested it yet. There was also this message on asterisk-security mailing list http://archives.free.net.ph/message/20070507.101933.222987b2.en.html which got no answers and this makes me think that this iax encryption is not much interesting for the community. Anyway, in iax specification there is this statement: "Only the data portion of the messages are encoded." Which are the consequences of this, is it true as stated on http://www.voip-info.org/wiki/view/IAX+encryption that "The calling/called numbers are still passed in the clear over encrypted IAX, so you are still vulnerable to traffic analysis." ? If it's true how to deal with this? Would you consider media payload encryption enough? Maybe it's better to just forget about iax encryption and consider some more general approach like using openvpn http://www.voip-info.org/wiki/view/IAX_OpenVPN ? This half-encrypted iax encryption doesn't make much sense to me, therefore I think there's probably something I'm missing/misunderstanding. Best Regards, Claudio Internet Email Confidentiality Footer ----------------------------------------------------------------------------------------------------- La presente comunicazione, con le informazioni in essa contenute e ogni documento o file allegato, e' rivolta unicamente alla/e persona/e cui e' indirizzata ed alle altre da questa autorizzata/e a riceverla. Se non siete i destinatari/autorizzati siete avvisati che qualsiasi azione, copia, comunicazione, divulgazione o simili basate sul contenuto di tali informazioni e' vietata e potrebbe essere contro la legge (art. 616 C.P., D.Lgs n. 196/2003 Codice in materia di protezione dei dati personali). Se avete ricevuto questa comunicazione per errore, vi preghiamo di darne immediata notizia al mittente e di distruggere il messaggio originale e ogni file allegato senza farne copia alcuna o riprodurne in alcun modo il contenuto. This e-mail and its attachments are intended for the addressee(s) only and are confidential and/or may contain legally privileged information. If you have received this message by mistake or are not one of the addressees above, you may take no action based on it, and you may not copy or show it to anyone; please reply to this e-mail and point out the error which has occurred. -----------------------------------------------------------------------------------------------------

tilghman at mail.jeffa...
Guest

Posted: Wed Feb 06, 2008 7:36 pm Post subject: [asterisk-users] is encrypted iax safe and secure?

On Tuesday 05 February 2008 09:22:29 Cavalera Claudio Luigi wrote:

Quote:

Hello,
I'm doing some research concerning iax encryption, I haven't find any
clients (softphones or hardphones) which implement so I have not tested
it yet.

There was also this message on asterisk-security mailing list
http://archives.free.net.ph/message/20070507.101933.222987b2.en.html
which got no answers and this makes me think that this iax encryption is
not much interesting for the community.

Anyway, in iax specification there is this statement:
"Only the data portion of the messages are encoded."

Which are the consequences of this, is it true as stated on
http://www.voip-info.org/wiki/view/IAX+encryption
that
"The calling/called numbers are still passed in the clear over encrypted
IAX, so you are still vulnerable to traffic analysis."
?

If it's true how to deal with this?
Would you consider media payload encryption enough?
Maybe it's better to just forget about iax encryption and consider some
more general approach like using openvpn
http://www.voip-info.org/wiki/view/IAX_OpenVPN ?

This half-encrypted iax encryption doesn't make much sense to me,
therefore I think there's probably something I'm
missing/misunderstanding.

Is it important for you to conceal that a call was made from abc to xyz on
thus-and-such a date? Or do you merely need to conceal the content of a
call? You can already do traffic analysis and figure out that a call
occurred, just not what the endpoints are (even if you encrypted the entire
link). The only way to get around that is to continuously send random garbage
through the pipe at the same rate and consistency as would occur with a real
IAX2 call. And the endpoints are only as specific as the systems on either
end choose to make them. If you used some system of src/dst obfuscation, you
could conceal even that information, though repeated calls to various
destinations could still be paired and correlated.

IAX2 encryption is designed to obscure the same information as is obscured
when you encrypt a call over the PSTN -- the content is protected, but the
existence of such a call is not. Remember that a potential attacker will
always choose the weakest link, and will probably attack the audio stream
at a different location, if she cannot listen to the IP stream directly (such
as a true wiretap on an analog endpoint or breaking into one of the two
machines involved in the encryption). The idea is to make the IAX2 link
unattractive as a potential target of wiretapping (whereas before it would
have been the most obvious choice), thus forcing the attacker to choose a
different attack scenario.

--
Tilghman

thp at westhawk.co.uk
Guest

Posted: Thu Feb 07, 2008 6:11 am Post subject: [asterisk-users] is encrypted iax safe and secure?

On 7 Feb 2008, at 00:36, Tilghman Lesher wrote:

Quote:

On Tuesday 05 February 2008 09:22:29 Cavalera Claudio Luigi wrote:

Quote:

Hello,
I'm doing some research concerning iax encryption, I haven't find any
clients (softphones or hardphones) which implement so I have not
tested
it yet.

There was also this message on asterisk-security mailing list
http://archives.free.net.ph/message/20070507.101933.222987b2.en.html
which got no answers and this makes me think that this iax
encryption is
not much interesting for the community.

Anyway, in iax specification there is this statement:
"Only the data portion of the messages are encoded."

Which are the consequences of this, is it true as stated on
http://www.voip-info.org/wiki/view/IAX+encryption
that
"The calling/called numbers are still passed in the clear over
encrypted
IAX, so you are still vulnerable to traffic analysis."
?

If it's true how to deal with this?
Would you consider media payload encryption enough?
Maybe it's better to just forget about iax encryption and consider
some
more general approach like using openvpn
http://www.voip-info.org/wiki/view/IAX_OpenVPN ?

This half-encrypted iax encryption doesn't make much sense to me,
therefore I think there's probably something I'm
missing/misunderstanding.

Is it important for you to conceal that a call was made from abc to
xyz on
thus-and-such a date? Or do you merely need to conceal the content
of a
call? You can already do traffic analysis and figure out that a call
occurred, just not what the endpoints are (even if you encrypted the
entire
link). The only way to get around that is to continuously send
random garbage
through the pipe at the same rate and consistency as would occur
with a real
IAX2 call. And the endpoints are only as specific as the systems on
either
end choose to make them. If you used some system of src/dst
obfuscation, you
could conceal even that information, though repeated calls to various
destinations could still be paired and correlated.

IAX2 encryption is designed to obscure the same information as is
obscured
when you encrypt a call over the PSTN -- the content is protected,
but the
existence of such a call is not. Remember that a potential attacker
will
always choose the weakest link, and will probably attack the audio
stream
at a different location, if she cannot listen to the IP stream
directly (such
as a true wiretap on an analog endpoint or breaking into one of the
two
machines involved in the encryption). The idea is to make the IAX2
link
unattractive as a potential target of wiretapping (whereas before it
would
have been the most obvious choice), thus forcing the attacker to
choose a
different attack scenario.

--
Tilghman

________________________

Also if you _really_ care about concealing the dialed number
you can do it just fine.

The simplest way is to have a single exten that takes _all_ encrypted
calls,
then once the call is up, dial 'onwards' with DTMF, the DTMF frames
would
be encrypted.

In fact IAX kinda supports this at the protocol level (although I
don't know of a working implementation
apart from the iAXy perhaps, but that doesn't do crypto...).

The NEW frame doesn't _have_ to contain a dialed number, the digits
can be sent later
(I forget the frametype), but later means within the encrypted
session Smile

Tim.

Claudio.Cavalera at it...
Guest

Posted: Wed Feb 13, 2008 10:55 am Post subject: [asterisk-users] is encrypted iax safe and secure?

asterisk-users-bounces at lists.digium.com wrote:

Quote:

Is it important for you to conceal that a call was made from
abc to xyz on
thus-and-such a date? Or do you merely need to conceal the
content of a
call?

I was thinking about concealing called and calling number in a generic
iax2 call, I hadn't even thinked about concealing the call itself. Smile

Another not so related question, during iax2 registration is "username"
Information Element always sent in clear?
I guess it is in clear since the first REGREQ even in the case of RSA or
MD5 based authentication.

Thanks,
Claudio
Internet Email Confidentiality Footer
-----------------------------------------------------------------------------------------------------
La presente comunicazione, con le informazioni in essa contenute e ogni documento o file allegato, e' rivolta unicamente alla/e persona/e cui e' indirizzata ed alle altre da questa autorizzata/e a riceverla. Se non siete i destinatari/autorizzati siete avvisati che qualsiasi azione, copia, comunicazione, divulgazione o simili basate sul contenuto di tali informazioni e' vietata e potrebbe essere contro la legge (art. 616 C.P., D.Lgs n. 196/2003 Codice in materia di protezione dei dati personali). Se avete ricevuto questa comunicazione per errore, vi preghiamo di darne immediata notizia al mittente e di distruggere il messaggio originale e ogni file allegato senza farne copia alcuna o riprodurne in alcun modo il contenuto.

This e-mail and its attachments are intended for the addressee(s) only and are confidential and/or may contain legally privileged information. If you have received this message by mistake or are not one of the addressees above, you may take no action based on it, and you may not copy or show it to anyone; please reply to this e-mail and point out the error which has occurred.
-----------------------------------------------------------------------------------------------------

kpfleming at digium.com
Guest

Posted: Fri Feb 15, 2008 12:31 pm Post subject: [asterisk-users] is encrypted iax safe and secure?

Tim Panton wrote:

Quote:

The NEW frame doesn't _have_ to contain a dialed number, the digits
can be sent later
(I forget the frametype), but later means within the encrypted
session Smile

It's the DIAL command that you are thinking of. I'm considering
implementing this, but it has one major caveat: to really do the job
right, we wouldn't want any caller information (CLID or CNAM) to be in
the NEW message either, it would have to be added as IEs to the DIAL
command. Unfortunately no existing implementations are going to be
prepared to receive that information as part of DIAL, so they would
process this sort of call with an empty CLID and CNAM. We can of course
enhance chan_iax2 to understand this method of doing things, but it
won't be backward compatible with previous versions of Asterisk or any
other IAX2 clients.

--
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)

stevej456 at gmail.com
Guest

Posted: Fri Feb 15, 2008 1:57 pm Post subject: [asterisk-users] is encrypted iax safe and secure?

Of course *it would be nice if* the IAX2 authentication parameters
were also encrypted, so that there was no danger of a 3rd party
hijacking your connection and generating a bunch of extra charges.

S.

On Fri, Feb 15, 2008 at 11:31 AM, Kevin P. Fleming <kpfleming at digium.com> wrote:

Quote:

Tim Panton wrote:

Quote:

The NEW frame doesn't _have_ to contain a dialed number, the digits
can be sent later
(I forget the frametype), but later means within the encrypted
session Smile

kpfleming at digium.com
Guest

Posted: Mon Feb 18, 2008 10:12 am Post subject: [asterisk-users] is encrypted iax safe and secure?

Steve Johnson wrote:

Quote:

Of course *it would be nice if* the IAX2 authentication parameters
were also encrypted, so that there was no danger of a 3rd party
hijacking your connection and generating a bunch of extra charges.

Can you elaborate? I don't see any way that a connection can be
'hijacked' as you put it.

--
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)

Claudio.Cavalera at it...
Guest

Posted: Mon Feb 18, 2008 10:43 am Post subject: [asterisk-users] is encrypted iax safe and secure?

Quote:

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of
Kevin P. Fleming
Sent: Monday, February 18, 2008 4:13 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] is encrypted iax safe and secure?

Steve Johnson wrote:

Quote:

Of course *it would be nice if* the IAX2 authentication parameters
were also encrypted, so that there was no danger of a 3rd party
hijacking your connection and generating a bunch of extra charges.

Can you elaborate? I don't see any way that a connection can be
'hijacked' as you put it.

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