On Fri, Feb 20, 2009 at 8:28 PM, Dean Willis <[email protected]> wrote:

> Of course, that doesn't help with an attack mode that turns UAs into
> amplifiers . . .

Well, luckily UAs could more easily remain stateless when rejecting
responses than proxies, as they don't need to worry about things like
forking (be it parallel or serial - e.g due to next hop SRV
processing), so should be able to commonly respond to failure
responses statelessly.

This specific attack only arises when a there can be a invite server
transaction created directly by a UDP request that has not been
authenticated, and doesn't contain a "via cookie"

alas, every UA implementation i've played with to date has almost
always been stateful for even failure responses sent over UDP that
havn't required a large amount of processing (or any variance) to
reach it, except for some very low level induced responses like
malformed header fields.

 ~ Theo
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