Ubuntu: USN-3346-2: Bind regression

USN-3346-1 fixed vulnerabilities in Bind. The fix forCVE-2017-3142 introduced a regression in the ability to receive an AXFR or IXFR in the case where TSIG is used and not every message is signed. This update fixes the problem.

In addition, this update adds the new root zone key signing key (KSK).

Original advisory details:

Clément Berthaux discovered that Bind did not correctly check TSIG authentication for zone update requests. An attacker could use this to improperly perform zone updates. (CVE-2017-3143) Clément Berthaux discovered that Bind did not correctly check TSIG authentication for zone transfer requests. An attacker could use this to improperly transfer entire zones. (CVE-2017-3142)