28 Jul
2004
28 Jul
'04
2 p.m.
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ? Or maybe there are some other counter measures
against such fraud?
Does src_ip comes directly from ip layer? If so, i could probably use this
to check with some external database (ie. ser subscriber)?
Antanas
NTT
28 Jul
28 Jul
2:12 p.m.
zolia(a)z1sys.com wrote:
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ?
this doesn't work. for each authentication challenge, ser generates an
noun that is kept into memory for a short period of time. So, this kind
of exploit is very limited - only if somebody trys in real time to do it
and in very narrow time window.
IP checking doesn't help you - they can be also spoof. Plus, against
what address you check when the user register for the first time? or if
the user use multiple client in the same time?
bogdan
Or maybe there are some other counter measures
against such fraud?
Does src_ip comes directly from ip layer? If so, i could probably use this
to check with some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
2:30 p.m.
Hi all,
always about this...is it possible to do IP accounting by acc module,
introducing something like to another parameter of log_mft for the Contact
(if applicable) Header Field in the INVITE, BYE method?
Thanks in advance.
Franz
----- Original Message -----
From: "Bogdan-Andrei IANCU" <iancu(a)fokus.fraunhofer.de>
To: <zolia(a)z1sys.com>
Cc: <serusers(a)lists.iptel.org>
Sent: Wednesday, July 28, 2004 2:12 PM
Subject: Re: [Serusers] account + IP binding
zolia(a)z1sys.com wrote:
this
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ?
this doesn't work. for each authentication challenge, ser generates an
noun that is kept into memory for a short period of time. So, this kind
of exploit is very limited - only if somebody trys in real time to do it
and in very narrow time window.
IP checking doesn't help you - they can be also spoof. Plus, against
what address you check when the user register for the first time? or if
the user use multiple client in the same time?
bogdan
> Or maybe there are some other counter measures
>against such fraud?
>
>Does src_ip comes directly from ip layer? If so, i could probably use to check with
some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
2:40 p.m.
Francesco Bottà wrote:
Hi all,
always about this...is it possible to do IP accounting by acc module,
introducing something like to another parameter of log_mft for the Contact
(if applicable) Header Field in the INVITE, BYE method?
I see no immediate purpose of logging contact? or...?
bogdan
Thanks in advance.
Franz
----- Original Message -----
From: "Bogdan-Andrei IANCU" <iancu(a)fokus.fraunhofer.de>
To: <zolia(a)z1sys.com>
Cc: <serusers(a)lists.iptel.org>
Sent: Wednesday, July 28, 2004 2:12 PM
Subject: Re: [Serusers] account + IP binding
zolia(a)z1sys.com wrote:
this
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ?
this doesn't work. for each authentication challenge, ser generates an
noun that is kept into memory for a short period of time. So, this kind
of exploit is very limited - only if somebody trys in real time to do it
and in very narrow time window.
IP checking doesn't help you - they can be also spoof. Plus, against
what address you check when the user register for the first time? or if
the user use multiple client in the same time?
bogdan
>Or maybe there are some other counter measures
>against such fraud?
>
>Does src_ip comes directly from ip layer? If so, i could probably use
>
> to check
with some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
2:57 p.m.
On Wed, 28 Jul 2004, Bogdan-Andrei IANCU wrote:
zolia(a)z1sys.com wrote:
yes probably, is would work only in real time, ie.
to write some small
proxy, which rewrites authorization header putting in in parallel sniffed
encrypted password. Its a bit harder..
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ?
this doesn't work. for each authentication challenge, ser generates an
noun that is kept into memory for a short period of time. So, this kind
of exploit is very limited - only if somebody trys in real time to do it
and in very narrow time window. IP checking doesn't help you - they can be also
spoof. Plus, against
what address you check when the user register for the first time? or if
What do you
mean by "first time"? If there are only one IP from which UA
requests MUST originate, then it should be possible to check it.
the user use multiple client in the same time?
This would not be possible in our scenario.
Antanas
bogdan
Or maybe there are some other counter measures
against such fraud?
Does src_ip comes directly from ip layer? If so, i could probably use this
to check with some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
1 Aug
1 Aug
10:28 p.m.
No, but I have this on my todo list. Currently it is possible to re-use
credentials generated by user agent A also by user agent B provided that
it can sniff the SIP messages and it is fast enough to send another
message including the sniffed credentials. The credentials have limited
lifetime (1 minute by default) so after 1 minute they cannot be re-used
in other SIP messages.
If you have two user agents connected to the same hub (so that they can
see SIP messages of each other) then you can modify one of them to steal
the calls to the other user agent using sniffed digest credentials.
I am thinking about including the source IP address of the SIP message
and some other header fields (Contact) into nonce to eliminate this
weakness.
Jan.
On 28-07 15:00, zolia(a)z1sys.com wrote:
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ? Or maybe there are some other counter measures
against such fraud?
Does src_ip comes directly from ip layer? If so, i could probably use this
to check with some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
2 Aug
2 Aug
10:03 a.m.
hi,
As i understand it would be virtually impossible to replay with proper
timestamp for certain request and with required ip, but nevetheless it
would be possible to fake required source_ip and in that case my patch
(posted earlier on this list) wouldn't help too. Adding source ip to nonce
would remove additional administrative burden, isn't it? Probably the only
advanatage of authorization by entering IP adresses separately would be
independance from any other encryption or authorization mechanisms which
could be used with SIP.
Antanas
On Sun, 1 Aug 2004, Jan Janak wrote:
No, but I have this on my todo list. Currently it is
possible to re-use
credentials generated by user agent A also by user agent B provided that
it can sniff the SIP messages and it is fast enough to send another
message including the sniffed credentials. The credentials have limited
lifetime (1 minute by default) so after 1 minute they cannot be re-used
in other SIP messages.
If you have two user agents connected to the same hub (so that they can
see SIP messages of each other) then you can modify one of them to steal
the calls to the other user agent using sniffed digest credentials.
I am thinking about including the source IP address of the SIP message
and some other header fields (Contact) into nonce to eliminate this
weakness.
Jan.
On 28-07 15:00, zolia(a)z1sys.com wrote:
hello,
is it possible to do source ip authentication besides normal
www_authorize() for every user account?. This, as i understand, should
prevent from intercepting credentials and later faking sip message to
bypass www_authorization ? Or maybe there are some other counter measures
against such fraud?
Does src_ip comes directly from ip layer? If so, i could probably use this
to check with some external database (ie. ser subscriber)?
Antanas
NTT
_______________________________________________
Serusers mailing list
serusers(a)lists.iptel.org
http://lists.iptel.org/mailman/listinfo/serusers
5:36 p.m.
Yes, that's right. We could also include the value of Contact header
field into nonce. That way it won't be possible to reuse the same nonce
for another Contact header field.
nonce string will be generate for Contact: A, another user agent trying
to reuse the digest credentials with Contact: B to steal incoming calls
will fail because the contact in nonce and Contact in the SIP message
will not match.
Jan.
On 02-08 11:03, Antanas Masevicius wrote:
hi,
As i understand it would be virtually impossible to replay with proper
timestamp for certain request and with required ip, but nevetheless it
would be possible to fake required source_ip and in that case my patch
(posted earlier on this list) wouldn't help too. Adding source ip to nonce
would remove additional administrative burden, isn't it? Probably the only
advanatage of authorization by entering IP adresses separately would be
independance from any other encryption or authorization mechanisms which
could be used with SIP.
Antanas
On Sun, 1 Aug 2004, Jan Janak wrote:
> No, but I have this on my todo list. Currently it is possible to re-use
> credentials generated by user agent A also by user agent B provided that
> it can sniff the SIP messages and it is fast enough to send another
> message including the sniffed credentials. The credentials have limited
> lifetime (1 minute by default) so after 1 minute they cannot be re-used
> in other SIP messages.
>
> If you have two user agents connected to the same hub (so that they can
> see SIP messages of each other) then you can modify one of them to steal
> the calls to the other user agent using sniffed digest credentials.
>
> I am thinking about including the source IP address of the SIP message
> and some other header fields (Contact) into nonce to eliminate this
> weakness.
>
> Jan.
>
> On 28-07 15:00, zolia(a)z1sys.com wrote:
> > hello,
> >
> > is it possible to do source ip authentication besides normal
> > www_authorize() for every user account?. This, as i understand, should
> > prevent from intercepting credentials and later faking sip message to
> > bypass www_authorization ? Or maybe there are some other counter measures
> > against such fraud?
> >
> > Does src_ip comes directly from ip layer? If so, i could probably use this
> > to check with some external database (ie. ser subscriber)?
> >
> > Antanas
> > NTT
> >
> > _______________________________________________
> > Serusers mailing list
> > serusers(a)lists.iptel.org
> > http://lists.iptel.org/mailman/listinfo/serusers
>
7207
days inactive
7212
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7 comments
5 participants
participants (5)
-
Antanas Masevicius -
Bogdan-Andrei IANCU -
Francesco Bottà -
Jan Janak -
zolia＠z1sys.com