Hi,
The Intercept just published a few very interesting slides how the NSA intercepts H.323 (and SIP and Skype) VoIP traffic:
https://firstlook.org/theintercept/document/2014/03/12/vpn-voip-exploitation...
Notice how the HAMMERSTEIN component on page 4 "processes" the call signaling as man-in-the-middle. This would pretty much match the attack I have been warning about previously when I wrote "Why your AES encryption might be worth nothing".
http://www.gnugk.org/h323-encryption.html
Another interesting fact seems to be that they targeted H.323 and SIP before taking on Skype (bottom of page 2).
Regards, Jan
Jan,
There is no doubt that we need to improve security. Most of the H.323 and SIP networks follow a transitive trust model. That wouldn't be so bad, except there appear to be multiple weaknesses with TLS certificates.
Are they able to compromise a certificate without creating a bogus certificate? Or are they using bogus certificates? (The latter is actually trivial for them to do. Most people would never recognize that a bogus certificate was employed.)
Both H.323, SIP, and the forthcoming H.325, we need to take additional steps to fight against MiTM attacks. It's likely impossible to remove the transitive trust element, though.
Paul
------ Original Message ------ From: "Jan Willamowius" jan@willamowius.de To: "openh323gk-users@lists.sourceforge.net" openh323gk-users@lists.sourceforge.net Cc: h323implementers@lists.packetizer.com Sent: 3/13/2014 12:04:18 PM Subject: [h323implementers] NSA H.323 surveilance
Hi,
The Intercept just published a few very interesting slides how the NSA intercepts H.323 (and SIP and Skype) VoIP traffic:
https://firstlook.org/theintercept/document/2014/03/12/vpn-voip-exploitation...
Notice how the HAMMERSTEIN component on page 4 "processes" the call signaling as man-in-the-middle. This would pretty much match the attack I have been warning about previously when I wrote "Why your AES encryption might be worth nothing".
http://www.gnugk.org/h323-encryption.html
Another interesting fact seems to be that they targeted H.323 and SIP before taking on Skype (bottom of page 2).
Regards, Jan
-- Jan Willamowius, Founder of the GNU Gatekeeper Project EMail : jan@willamowius.de Website: http://www.gnugk.org Support: http://www.willamowius.com/gnugk-support.html
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Paul,
right now nobody is even using TLS. Decrypting H.323 currently is like taking candy from a baby.
While TLS can and should be improved, simply starting to use it would considerably raise the bar for any eavesdropper.
The transitive trust model means I have to trust my and my partners gatekeeper. But thats still a lot better than exposing all my secrets to everybody like we currently do. This is not the fault of the ITU specs which specify that implementers must encrypt the key negotiation. Its the fault of vendors failing to implement them correctly.
Regards, Jan
participants (2)
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Jan Willamowius -
Paul E. Jones