T1571 - Non-Standard Port

Adversaries may communicate using a protocol and port pairing that are typically not associated. For example, HTTPS over port 8088(Citation: Symantec Elfin Mar 2019) or port 587(Citation: Fortinet Agent Tesla April 2018) 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.

Adversaries may also make changes to victim systems to abuse non-standard ports. For example, Registry keys and other configuration settings can be used to modify protocol and port pairings.(Citation: change_rdp_port_conti)

Atomic Tests

Atomic Test #1 - Testing usage of uncommonly used port with PowerShellTesting uncommonly used port utilizing PowerShell. APT33 has been known to attempt telnet over port 8081. Upon execution, details about the successful

port check will be displayed. Supported Platforms: windows#### Attack Commands: Run with powershell

Test-NetConnection -ComputerName google.com -port 8081

Invoke-AtomicTest T1571 -TestNumbers 1

Atomic Test #2 - Testing usage of uncommonly used port

Testing uncommonly used port utilizing telnet.

Supported Platforms: linux, macos

Dependencies: Run with sh!

Description: Requires telnet

Check Prereq Commands:

which telnet

Get Prereq Commands:

echo "please install telnet to run this test"; exit 1

Invoke-AtomicTest T1571 -TestNumbers 2 -GetPreReqs

Attack Commands: Run with sh

echo quit | telnet google.com 8081
exit 0

Invoke-AtomicTest T1571 -TestNumbers 2

Detection

Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.(Citation: University of Birmingham C2)

Shield Active Defense

Network Monitoring

Monitor network traffic in order to detect adversary activity.

Network monitoring involves capturing network activity data, including capturing of server, firewall, and other relevant logs. A defender can then review them or send them to a centralized collection location for further analysis.

Opportunity

There is an opportunity to monitor network traffic for different protocols, anomalous traffic patterns, transfer of data, etc. to determine the presence of an adversary.

Use Case

The defender can implement network monitoring for and alert on anomalous traffic patterns, large or unexpected data transfers, and other activity that may reveal the presence of an adversary.

Procedures

Capture network logs for internet-facing devices and send those logs to a central collection location. Capture all network device (router, switches, proxy, etc.) logs on a decoy network and send those logs to a central collection location.