Windows: RDP to HTTP or HTTPS Target Ports

Rule ID

PH_Rule_SIGMA_1775

Default Status

Enabled

Description

Detects svchost hosting RDP termsvcs communicating to target systems on TCP port 80 or 443. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_rdp_to_http.yml

Severity

MITRE ATT&CK® Tactics

Command And Control

MITRE ATT&CK® Techniques

T1572

Protocol Tunneling

Adversaries may tunnel network communications to and from a victim system within a separate protocol to avoid detection/network filtering and/or enable access to otherwise unreachable systems. This behavior may conceal malicious traffic by blending in with existing traffic and/or provide an outer layer of encryption (similar to a VPN). Tunneling could also enable routing of network packets that would otherwise not reach their intended destination, such as SMB, RDP, or other traffic that would be filtered by network appliances or not routed over the Internet. Adversaries may perform SSH tunneling (also known as SSH port forwarding), DNS over HTTPS (DoH), queries to resolve C2 communications and infrastructure.

https://attack.mitre.org/techniques/T1572

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 procName REGEXP "\\svchost\.exe$" AND initiated="true" AND srcIpPort=3389 AND destIpPort IN (443,80)

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

destIpPort,hostName,initiated,procName,srcIpPort

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

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

FortiSIEM Rules