T1071 - Application Layer Protocol

Adversaries may communicate using OSI 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 server.

Adversaries may utilize many different protocols, including those used for web browsing, transferring files, electronic mail, or DNS. For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), commonly used protocols are SMB, SSH, or RDP.

Atomic Tests:

Currently, no tests are available for this technique.

Detection

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. Analyze packet contents to detect application layer protocols that do not follow the expected protocol standards regarding syntax, structure, or any other variable adversaries could leverage to conceal data.(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.