Has anyone seen or heard of SIP stack attacks (e.g. stack difference or stack fingerprinting) being used in the wild? http://www.blackhat.com/presentations/bh-usa-06/BH-US-06-Scholz.pdf talks very briefly about the possibility of using implementation bugs in an attack. It seems to me that the most likely effect of such an attack would be to crash the SIP process on the UA (DoS), but authentication bypassing could also be possible if the attacker got lucky. If such an attack is possible (a big 'if'), I suspect it would be very hard to execute; the risk from such attacks appears low. To put this into context, I'm wondering how paranoid to be when configuring my Acme Packet SBC. It's possible to blacklist any endpoint which sends malformed SIP messages, but that seems like a bit of an overreaction. Cheers, Paul