It was found that when NTP is configured in broadcast mode, an off-path attacker could broadcast packets with bad authentication (wrong key, mismatched key, incorrect MAC, etc) to all clients. The clients, upon receiving the malformed packets, would break the association with the broadcast server. This could cause the time on affected clients to become out of sync over a longer period of time. Upstream patch: https://github.com/ntp-project/ntp/commit/fe46889f7baa75fc8e6c0fcde87706d396ce1461
External References: http://support.ntp.org/bin/view/Main/SecurityNotice#January_2016_NTP_4_2_8p6_Securit http://www.talosintel.com/reports/TALOS-2016-0076/
Created ntp tracking bugs for this issue: Affects: fedora-all [bug 1300277]
Mitigation: Do not use NTP's broadcast mode by not configuring the "broadcast" directive in the ntp.conf file.
Statement: This issue affects the versions of ntp as shipped with Red Hat Enterprise Linux 5, 6, and 7. Red Hat Product Security has rated this issue as having Moderate security impact. A future update may address this issue in Red Hat Enterprise Linux 6 and 7. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.
ntp-4.2.6p5-36.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
ntp-4.2.6p5-36.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 6 Via RHSA-2016:1141 https://access.redhat.com/errata/RHSA-2016:1141
This issue has been addressed in the following products: Red Hat Enterprise Linux 6.7 Extended Update Support Via RHSA-2016:1552 https://rhn.redhat.com/errata/RHSA-2016-1552.html
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2016:2583 https://rhn.redhat.com/errata/RHSA-2016-2583.html