Amazon Linux AMI Security Advisory: ALAS-2014-370
Advisory Release Date: 2014-09-19 10:35 Pacific
A quoting issue was found in chkrootkit which would lead to a file in /tmp/ being executed, if /tmp/ was mounted without the noexec option. chkrootkit is typically run as the root user. A local attacker could use this flaw to escalate their privileges.
Run yum update chkrootkit to update your system.