Excessive Repeated DNS Queries To Same Domain

Rule ID

PH_Rule_Flow_18

Default Status

Enabled

Description

Detects an usually high frequency of DNS name resolution queries from the same host to the same domain name in a short period of time. This is not expected behavior since, in a typical scenario, the domain name resolution is cached at the end point. Repeated queries indicates that a special DNS client is likely running at the end host that is trying to make use of fast flux techniques to get back many infected hosts behind a crafted domain name.

Severity

MITRE ATT&CK® Tactics

Command And Control

MITRE ATT&CK® Techniques

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/T1568/001

Impacts

Application

Data Source

Network Traffic

Detection

Correlation

Remediation Guidance

No remediation guidance specified

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

ExcessRepeatDNS

SubPattern Definitions

SubPattern Name: ExcessRepeatDNS

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType IN (Group@PH_SYS_EVENT_CommonDNSTraffic)

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

srcIpAddr, destName

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT (*) >= 100

Incident Attribute Mapping

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 = ExcessRepeatDNS.srcIpAddr,
 destName =ExcessRepeatDNS.destName,
 incidentCount = ExcessRepeatDNS.COUNT (*)

FortiSIEM Rules