NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38.
ntp-4.2.8p15
was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.
Please see the NTP Security Notice for vulnerability and mitigation details.Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
ntpd
may be susceptible to IPv4 attack from highly predictable transmit timestamps ntpd
up to, but not including ntp-4.2.8p14 and ntp-4.3.100. Resolved in ntp-4.2.8p14 and ntp-4.3.100.
ntpd
instance that gets its time from unauthenticated IPv4 time sources may be vulnerable to an off-path attacker who can query time from the victim's ntpd
instance. The attacker must be able to send and the victim must be able to receive and process a large number of packets with the spoofed IPv4 address of the upstream server. After 8 or more successful attacks in a row, the attacker can either modify the victim's clock by a limited amount or cause ntpd
to exit. This attack is most effective in cases where an unusually short poll interval is expressly configured on the victim's ntpd
.
ntpd
.
ntpd
instances. If the pstats
command of ntpq
shows the value for "bogus origin" is increasing then that association is likely under attack.
restrict ... noserve
to prevent this attack (note that this is a heavy-handed protection), which blocks time service to the specified network.
ntp.conf
file: server ... xmtnonce
pool ... xmtnonce
restrict ... serverresponse fuzz
pollskewlist default 6|6
(for example)