PH_Rule_Stat_12
Enabled
Detects sudden increase in DNS requests from a specific source IP - over a 15 minute period, a particular source IP is doing excessive DNS requests. Excessive DNS requests is defined as at least 100 requests and current count is 3 standard deviations away from mean for the current hour. Excessive Destination names is defined as 50 distinct name resolutions and current count is more than 3 standard deviations away from the mean for the current hour
7
Security
Command And Control
T1568.001
Dynamic Resolution: Fast Flux DNS
Adversaries may use Fast Flux DNS to hide a command and control channel behind an array of rapidly changing IP addresses linked to a single domain resolution. This technique uses a fully qualified domain name, with multiple IP addresses assigned to it which are swapped with high frequency, using a combination of round robin IP addressing and short Time-To-Live (TTL) for a DNS resource record.
https://attack.mitre.org/techniques/T1568/001Network
FortiGate via Syslog or Netflow, Cisco IOS via Syslog or Netflow, Checkpoint via Syslog or Netflow, Palo Alto via Syslog or Netflow
Profiling
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
900 seconds
If the following defined pattern/s occur within a 900 second time window.
DNSConn
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
destIpPort = 53 AND eventType IN (Group@PH_SYS_EVENT_PermitNetTraffic, Group@PH_SYS_EVENT_NetflowTraffic, Group@PH_SYS_EVENT_BiNetflowTraffic)
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
srcIpAddr
This is most typically a numerical constraint that defines when the rule should trigger an incident
(COUNT(*)-STAT_AVG(COUNT(*):113))/STAT_STDDEV(COUNT(*):113) >= 3 AND STAT_STDDEV(COUNT(*):113) > 0 AND COUNT(*) >= 100
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
srcIpAddr = DNSConn.srcIpAddr