Last Modified: Sep 13, 2023
Known Affected Versions:
15.1.4, 220.127.116.11, 15.1.5, 18.104.22.168, 15.1.6, 22.214.171.124, 15.1.7, 15.1.8, 126.96.36.199, 188.8.131.52, 15.1.9, 184.108.40.206, 15.1.10, 16.1.2, 220.127.116.11, 18.104.22.168, 16.1.3, 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, 16.1.4
Opened: Dec 29, 2021 Severity: 3-Major
When the DNS cache is activated, the NXDOMAIN DoS vector does not increase for the virtual server context. As a result, NXDOMAIN flood attack is never detected/mitigated at the virtual server context. Note this does not happen with other vectors like DNS A query flood attack, only for NXDOMAIN.
NXDOMAIN flood attack is never detected/mitigated at virtual server context.
Issue is only seen When DNS cache is activated and for NXDOMAIN Dos Vector.
Unbound is used to do the DNS query and the BIG-IP self IP is used to do the query instead of the listener at the server-side when DNS Cache is Enabled. DOS on connflow is also done at the client-side egress when DNS Cache is enabled in case of NXDOMAIN.