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.
|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.|