NTP BUG 2978: Interleave-pivot

Last update: February 15, 2022 20:59 UTC (43fbd379b)


Summary

Resolved 4.2.8p7 26 Apr 2016
References Bug 2978 CVE-2016-1548
Affects All ntp-4 releases up to, but not including 4.2.8p7,
and 4.3.0 up to, but not including 4.3.92.
Resolved in 4.2.8p7.
CVSS2 Score MED 6.4 AV:N/AC:L/Au:N/C:N/I:P/A:P
CVSS3 Score MED 7.2 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L

Description

It is possible to change the time of an ntpd client or deny service to an ntpd client by forcing it to change from basic client/server mode to interleaved symmetric mode. An attacker can spoof a packet from a legitimate ntpd server with an origin timestamp that matches the peer->dst timestamp recorded for that server. After making this switch, the client will reject all future legitimate server responses. It is possible to force the victim client to move time after the mode has been changed. ntpq gives no indication that the mode has been switched.


Mitigation


Credit

This weakness was discovered by Miroslav Lichvar of RedHat and separately by Jonathan Gardner of Cisco ASIG.


Timeline