The adversary is trying to communicate with and control compromised systems, controllers, and platforms with access to your ICS environment.
Command and Control consists of techniques that adversaries use to communicate with and send commands to compromised systems, devices, controllers, and platforms with specialized applications used in ICS environments. Examples of these specialized communication devices include human machine interfaces (HMIs), data historians, SCADA servers, and engineering workstations (EWS). Adversaries often seek to use commonly available resources and mimic expected network traffic to avoid detection and suspicion. For instance, commonly used ports and protocols in ICS environments, and even expected IT resources, depending on the target network. Command and Control may be established to varying degrees of stealth, often depending on the victim’s network structure and defenses.
| ID | Name | Description | |
| T0885 | Commonly Used Port | Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend in with normal network activity, to avoid more detailed inspection. They may use the protocol associated with the port, or a completely different protocol. They may use commonly open ports, such as the examples provided below. | |
| T0884 | Connection Proxy | Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications. | |
| T0869 | Standard Application Layer Protocol | Adversaries may establish command and control capabilities over commonly used application layer protocols such as HTTP(S), OPC, RDP, telnet, DNP3, and modbus. These protocols may be used to disguise adversary actions as benign network traffic. Standard protocols may be seen on their associated port or in some cases over a non-standard port. Adversaries may use these protocols to reach out of the network for command and control, or in some cases to other infected devices within the network. | |
| .001 | 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. The DNS protocol serves an administrative function in computer networking and thus may be very common in environments. DNS traffic may also be allowed even before network authentication is completed. DNS packets contain many fields and headers in which data can be concealed. Often known as DNS tunneling, adversaries may abuse DNS to communicate with systems under their control within a victim network while also mimicking normal, expected traffic. |
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| .002 | Publish/Subscribe Protocols | Adversaries may communicate using publish/subscribe (pub/sub) application layer protocols 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 broker. | |