Amazon Linux AMI Security Advisory: ALAS-2016-708
Advisory Release Date: 2016-06-02 18:06 Pacific
Advisory Updated Date: 2016-06-03 19:44 Pacific
It was found that an ntpd client could be forced to change from basic client/server mode to the interleaved symmetric mode. A remote attacker could use a spoofed packet that, when processed by an ntpd client, would cause that client to reject all future legitimate server responses, effectively disabling time synchronization on that client. (CVE-2016-1548)
An out-of-bounds access flaw was found in the way ntpd processed certain packets. An authenticated attacker could use a crafted packet to create a peer association with hmode of 7 and larger, which could potentially (although highly unlikely) cause ntpd to crash. (CVE-2016-2518)
A flaw was found in the way libntp performed message authentication. An attacker able to observe the timing of the comparison function used in packet authentication could potentially use this flaw to recover the message digest. (CVE-2016-1550)
Assertion failure in ntpd on duplicate IPs on unconfig directives (CVE-2016-2516)
Run yum update ntp to update your system.