Command and Control (C2) Daemon

Overview

The C2 daemon is a service that listens to the command line client on a pair of named pipes. The client submits a command and its arguments to be run. The daemon executes the command and returns the output.

Protocol Overview

The command line client and the daemon communicate by transferring CBOR encoded data inside of CSP packets. This allows for a dynamic protocol and for simple passing of messages with varying data payloads.

These messages are passed between a client and the daemon. A client will initiate a C2 “command transaction” by issuing a request. A transaction is comprised of a command request which is processed by the command daemon and completed when the daemon returns a response.

Daemon Input Message Format

The daemon accepts a CSP packet containing an encoded CBOR payload with the following fields:

Field	Type	Use
MSG_TYPE	Int	Designates the command type
ARG_COUNT	Int	The number of arguments following the command
COMMAND_NAME	String	The command to be run
ARGS	Array	An array of argument values

Daemon Output Message Format

Upon a successful command request processing and execution the daemon will respond with a CSP packet containing an encoded CBOR payload with the following fields:

Field	Type	Use
RETURN_CODE	Int	The return code of the command that was run
EXEC_TIME	Double	The amount of time that the command took to run
OUTPUT	String	The stdout of the command that was run

If there is an error that occurs while processing a command request, the daemon will return an error packet containing the following fields:

Field	Type	Use
MSG_TYPE	Int	Designates the response type
ERROR_MSG	Int	The description of the error that occurred