Windows: DNS Exfiltration and Tunneling Tools Execution

Rule ID

PH_Rule_SIGMA_398

Default Status

Enabled

Description

Well-known DNS Exfiltration tools execution. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_dns_exfiltration_tools_execution.yml

Severity

MITRE ATT&CK® Tactics

Command And Control

MITRE ATT&CK® Techniques

T1048.001

Exfiltration Over Alternative Protocol: Exfiltration Over Symmetric Encrypted Non-C2 Protocol

Adversaries may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

https://attack.mitre.org/techniques/T1048/001

T1071.004

Application Layer Protocol: DNS

Adversaries may communicate using the Domain Name System (DNS) application layer protocol to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

https://attack.mitre.org/techniques/T1071/004

T1132.001

Data Encoding: Standard Encoding

Adversaries may encode data with a standard data encoding system to make the content of command and control traffic more difficult to detect. Common data encoding schemes include ASCII, Unicode, hexadecimal, Base64, and MIME. Some data encoding systems may also result in data compression, such as gzip.

https://attack.mitre.org/techniques/T1132/001

Impacts

Server

Data Source

Windows Sysmon via FortiSIEM Agent

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.

Filter

SubPattern Definitions

SubPattern Name: Filter

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="Win-Sysmon-1-Create-Process" AND (procName REGEXP "\\iodine\.exe$" OR procName REGEXP ".*\\dnscat2.*")

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

hostName,procName

Aggregate Constraint

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

COUNT(*) >= 1

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

 hostName = Filter.hostName,
procName = Filter.procName

FortiSIEM Rules