Amazon Linux AMI Security Advisory: ALAS-2018-1083
Advisory Release Date: 2018-09-19 23:35 Pacific
ntpd in ntp 4.2.x before 4.2.8p7 allows authenticated users that know the private symmetric key to create arbitrarily-many ephemeral associations in order to win the clock selection of ntpd and modify a victim's clock via a Sybil attack. This issue exists because of an incomplete fix for CVE-2016-1549 .(CVE-2018-7170 )
The ntpq and ntpdc command-line utilities that are part of ntp package are vulnerable to stack-based buffer overflow via crafted hostname. Applications using these vulnerable utilities with an untrusted input may be potentially exploited, resulting in a crash or arbitrary code execution under privileges of that application.(CVE-2018-12327 )
Run yum update ntp to update your system.