Transient Cyber Asset

What the technique is

Adversaries may target devices that are transient across ICS networks and external networks. Normally, transient assets are brought into an environment by authorized personnel and do not remain in that environment on a permanent basis. Transient assets are commonly needed to support management functions and may be more common in systems where a remotely managed asset is not feasible, external connections for remote access do not exist, or 3rd party contractor/vendor access is required. Adversaries may take advantage of transient assets in different ways. For instance, adversaries may target a transient asset when it is connected to an external network and then leverage its trusted access in another environment to launch an attack. They may also take advantage of installed applications and libraries that are used by legitimate end-users to interact with control system devices. Transient assets, in some cases, may not be deployed with a secure configuration leading to weaknesses that could allow an adversary to propagate malicious executable code, e.g., the transient asset may be infected by malware and when connected to an ICS environment the malware propagates onto other systems.

What MITRE says you would watch

• AN1877

  Monitor for network traffic originating from unknown/unexpected hardware devices. Local network traffic metadata (such as source MAC addressing) may be helpful in identifying transient assets. Networking devices such as switches may log when new client devices connect (e.g., SNMP notifications). Monitor for any logs documenting changes to network connection status to determine when a new connection has occurred, including the resulting addresses (e.g., IP, MAC) of devices on that network.