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-4.2.8p15was 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.
ntpdmay be susceptible to IPv4 attack from highly predictable transmit timestamps
ntpdup to, but not including ntp-4.2.8p14 and ntp-4.3.100. Resolved in ntp-4.2.8p14 and ntp-4.3.100.
ntpdinstance 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
ntpdinstance. 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
ntpdto exit. This attack is most effective in cases where an unusually short poll interval is expressly configured on the victim's
ntpdinstances. If the
ntpqshows the value for "bogus origin" is increasing then that association is likely under attack.
restrict ... noserveto prevent this attack (note that this is a heavy-handed protection), which blocks time service to the specified network.
server ... xmtnonce
pool ... xmtnonce
restrict ... serverresponse fuzz
pollskewlist default 6|6(for example)