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LIN7-4996 : Security Advisory - ntp - CVE-2015-7704

Created: Oct 22, 2015    Updated: Sep 8, 2018
Resolved Date: Nov 25, 2015
Previous ID: LIN4-33107
Found In Version:
Fix Version:
Severity: Standard
Applicable for: Wind River Linux 7
Component/s: Userspace


When ntpd as an NTP client receives a Kiss-of-Death (KoD) packet from the server to reduce its polling rate, it doesn't check if the originate timestamp in the reply matches the transmit timestamp from its request. An off-path attacker can send a crafted KoD packet to the client, which will increase the client's polling interval to a large value and effectively disable synchronization with the server.

This issue affects ntp versions 4.2.6 and 4.2.8 up to 4.2.8p3.

The attacker can find out to what server the client is currently synchronized by sending it a regular client mode packet and checking the refid field in the reply (the refid is IPv4 address or first four bytes of MD5 sum of IPv6 address).

Upstream bug:

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