NTP BUG 2978: Interleave-pivot
Last update: June 28, 2022 20:06 UTC (57417e17c)
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.
- Implement BCP-38.
- Upgrade to 4.2.8p7 or later, which prevents
ntpd from dynamically enabling interleave mode.
- Properly monitor your
This weakness was discovered by Miroslav Lichvar of RedHat and separately by Jonathan Gardner of Cisco ASIG.