Windows: Suspicious Typical Malware Back Connect Ports

Rule ID

PH_Rule_SIGMA_352

Default Status

Enabled

Description

Detects programs that connect to typical malware back connect ports based on statistical analysis from two different sandbox system databases. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_malware_backconnect_ports.yml

Severity

MITRE ATT&CK® Tactics

Command And Control

MITRE ATT&CK® Techniques

T1571

Non-Standard Port

Adversaries may communicate using a protocol and port paring that are typically not associated. For example, HTTPS over port 8088 or port 587, as opposed to the traditional port 443. Adversaries may make changes to the standard port used by a protocol to bypass filtering or muddle analysis/parsing of network data.

https://attack.mitre.org/techniques/T1571

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 REGEXP "Win-Sysmon-3-Network-Connect.*" AND ((initiated="true" AND destIpPort IN (100,10101,12102,12103,12322,13145,13394,13504,13505,13506,13507,14102,14103,14154,1443,1515,1777,1817,1904,1960,198,200,243,2443,2448,3360,3675,3939,4040,4433,4438,4443,4444,4455,473,49180,5445,5552,5649,65520,65535,6625,666,700,7210,743,777,8080,8143,8843,8888,9631,9943)) AND ((destIpAddr NOT IN (Group@PH_SYS_NETWORK_ENTERPRISE_INTERNAL_NET)))) AND ((procName NOT REGEXP "^C:\\Program Files \(x86\)\\|^C:\\Program Files\\"))

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

destIpAddr,destIpPort,hostName,initiated,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

destIpAddr = Filter.destIpAddr,
destIpPort = Filter.destIpPort,
hostName = Filter.hostName,
initiated = Filter.initiated,
procName = Filter.procName

FortiSIEM Rules