CERT recently reported two Network Time Protocol (NTP) vulnerabilities (CERT VU#374268 April 7, 2015) . The first one concerns some versions of NTP Project software that will accept packets without authentication digests as if they actually had valid digests attached, and the second one describes a Denial of Service (DoS) scenario in which an attacker can prevent two peering systems from synchronizing. Neither NTP vulnerabilities affect Secure64 servers.
In the first case, no NTP Project code is used in the Secure64 NTP implementation. In this implementation, associations that specify the use of authentication digests require all incoming and outgoing packets to have attached digests; any incoming packet without the required authentication information is treated exactly like a packet with an invalid digest, and is dropped.
In the second case, Secure64 NTP never peers with external servers, but rather forms a consensus among servers using periodic timestamp queries. This approach is not as precise as traditional NTP peering, but provides timestamp resolution well within the requirements of DNSSEC signing operations. Since there is no peering being used, there is no way to disrupt a peering session, and hence no DoS vulnerability. This strategy conforms to the security best-practice of minimizing the code paths that are traversed, in order to maximize resistance to network exploits.