I'm reviewing CVE-2015-7850 and it says:

• Affects: All ntp-4 releases up to, but not including 4.2.8p4, and 4.3.0 up to, but not including 4.3.77

• Summary: If ntpd is configured to allow remote configuration, and if the (possibly spoofed) source IP address is allowed to send remote configuration requests, and if the attacker knows the remote configuration password or if ntpd was configured to disable authentication, then an attacker can send a set of packets to ntpd that will cause it to crash and/or create a potentially huge log file. Specifically, the attacker could enable extended logging, point the key file at the log file, and cause what amounts to an infinite loop.

I have hard time to udnerstand the following line:

If ntpd is configured to allow remote configuration

What does that mean?

1 Answer 1


ntpd can be configured remotely with the ntpdc command. See e.g. this for what you can do (add and remove servers e.g.). This is normally only enabled for localhost, if at all.

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