ICSNPP-DNP3

Industrial Control Systems Network Protocol Parsers (ICSNPP) - DNP3.

Overview

ICSNPP-DNP3 is a Zeek package that extends the logging capabilities of Zeek's default DNP3 protocol parser.

Zeek's default DNP3 parser logs DNP3 traffic to dnp3.log. This log file remains unchanged. This package extends DNP3 logging capability by adding two new DNP3 log files:

• dnp3_control.log
• dnp3_objects.log

For additional information on these log files, see the Logging Capabilities section below.

Installation

Package Manager

This script is available as a package for Zeek Package Manger

zkg refresh
zkg install icsnpp-dnp3

If ZKG is configured to load packages (see @load packages in quickstart guide), this script will automatically be loaded and ready to go. ZKG Quickstart Guide

If users are not using site/local.zeek or another site installation of Zeek and want to run this script on a packet capture, they can add icsnpp-dnp3 to the command to run this script on the packet capture:

git clone https://github.com/cisagov/icsnpp-dnp3.git
zeek -Cr icsnpp-dnp3/tests/traces/dnp3_example.pcap icsnpp-dnp3

Manual Install

To install this script manually, clone this repository and copy the contents of the scripts directory into ${ZEEK_INSTALLATION_DIR}/share/zeek/site/icsnpp-dnp3.

git clone https://github.com/cisagov/icsnpp-dnp3.git
zeek_install_dir=$(dirname $(dirname `which zeek`))
cp -r icsnpp-dnp3/scripts/ $zeek_install_dir/share/zeek/site/icsnpp-dnp3

If using a site deployment, simply add echo @load icsnpp-dnp3 to the local.site file.

If users are not using site/local.zeek or another site installation of Zeek, and want to run this package on a packet capture, they can add icsnpp-dnp3 to the command to run this plugin's scripts on the packet capture:

zeek -Cr icsnpp-dnp3/tests/traces/dnp3_example.pcap icsnpp-dnp3

Logging Capabilities

DNP3 Control Log (dnp3_control.log)

Overview

This log captures DNP3 Control Relay Output Block and Pattern Control Block data seen in SELECT-OPERATE-RESPONSE commands and logs them to dnp3_control.log.

DNP3 Control Relay Output Blocks can be controlled via DNP3 SELECT and OPERATE commands and are among the most common (and most impactful) DNP3 commands.

This log file contains all the relevant data for these SELECT and OPERATE commands (as well as the responses), it shows a more in-depth look at these commands, and it provides a much more detailed look at what operational DNP3 commands are being sent.

Fields Captured:

Field	Type	Description
ts	time	Timestamp
uid	string	Unique ID for this connection
id	conn_id	Default Zeek connection info (IP addresses, ports)
is_orig	bool	True if the packet is sent from the originator
source_h	address	Source IP address (see Source and Destination Fields)
source_p	port	Source port (see Source and Destination Fields)
destination_h	address	Destination IP address (see Source and Destination Fields)
destination_p	port	Destination port (see Source and Destination Fields)
block_type	string	Control_Relay_Output_Block or Pattern_Control_Block
function_code	string	Function code (SELECT, OPERATE, RESPONSE)
index_number	count	Object index number
trip_control_code	string	Nul, Close, or Trip
operation_type	string	Nul, Pulse_On, Pulse_Off, Latch_On, Latch_Off
execute_count	count	Number of times to execute
on_time	count	On time
off_time	count	Off time
status_code	string	Status code

DNP3 Read Object Log (dnp3_read_objects.log)

Overview

This log captures DNP3 Read Object data seen in READ-RESPONSE commands and logs them to dnp3_objects.log.

DNP3 READ-RESPONSE commands are very common DNP3 commands and these responses contain a lot of useful information about the DNP3 devices.

Fields Captured

Field	Type	Description
ts	time	Timestamp
uid	string	Unique ID for this connection
id	conn_id	Default Zeek connection info (IP addresses, ports)
is_orig	bool	True if the packet is sent from the originator
source_h	address	Source IP address (see Source and Destination Fields)
source_p	port	Source port (see Source and Destination Fields)
destination_h	address	Destination IP address (see Source and Destination Fields)
destination_p	port	Destination port (see Source and Destination Fields)
function_code	string	Function code (READ or RESPONSE)
object_type	string	DNP3 object type
object_count	count	Number of objects
range_low	count	Range (low) of object
range_high	count	Range (high) of object

Source and Destination Fields

Overview

Zeek's typical behavior is to focus on and log packets from the originator and not log packets from the responder. However, most ICS protocols contain useful information in the responses, so the ICSNPP parsers log both originator and responses packets. Zeek's default behavior, defined in its id struct, is to never switch these originator/responder roles which leads to inconsistencies and inaccuracies when looking at ICS traffic that logs responses.

The default Zeek id struct contains the following logged fields:

• id.orig_h (Original Originator/Source Host)
• id.orig_p (Original Originator/Source Port)
• id.resp_h (Original Responder/Destination Host)
• id.resp_p (Original Responder/Destination Port)

Additionally, the is_orig field is a boolean field that is set to T (True) when the id_orig fields are the true originators/source and F (False) when the id_resp fields are the true originators/source.

To not break existing platforms that utilize the default id struct and is_orig field functionality, the ICSNPP team has added four new fields to each log file instead of changing Zeek's default behavior. These four new fields provide the accurate information regarding source and destination IP addresses and ports:

• source_h (True Originator/Source Host)
• source_p (True Originator/Source Port)
• destination_h (True Responder/Destination Host)
• destination_p (True Responder/Destination Port)

The pseudocode below shows the relationship between the id struct, is_orig field, and the new source and destination fields.

if is_orig == True
    source_h == id.orig_h
    source_p == id.orig_p
    destination_h == id.resp_h
    destination_p == id.resp_p
if is_orig == False
    source_h == id.resp_h
    source_p == id.resp_p
    destination_h == id.orig_h
    destination_p == id.orig_p

Example

The table below shows an example of these fields in the log files. The first log in the table represents a Modbus request from 192.168.1.10 -> 192.168.1.200 and the second log represents a Modbus reply from 192.168.1.200 -> 192.168.1.10. As shown in the table below, the id structure lists both packets as having the same originator and responder, but the source and destination fields reflect the true source and destination of these packets.

id.orig_h	id.orig_p	id.resp_h	id.resp_p	is_orig	source_h	source_p	destination_h	destination_p
192.168.1.10	47785	192.168.1.200	502	T	192.168.1.10	47785	192.168.1.200	502
192.168.1.10	47785	192.168.1.200	502	F	192.168.1.200	502	192.168.1.10	47785

Coverage

See Logging Capabilities for detailed information of the parser coverage.

The DNP3 protocol contains a few vendor and product specific functions. These vendor/product specific functions are not included in this parser. All coverage details in this section include information and statistics based on the basic/default DNP3 protocol.

General/Header Logging

The general log file for DNP3 (dnp3.log) is produced by Zeek's default DNP3 parser and is not modified by this parser extension.

Detailed Logging

Detailed logging for 7 DNP3 functions are logged in the control log file (dnp3_control.log) and 2 DNP3 functions are logged in the objects log file (dnp3_objects.log). There are a total of 37 default DNP3 functions, however, 7 of these DNP3 functions do not contain any additional data to be logged. ~23% (7/30) of data containing default DNP3 functions contain detailed logging.

ICSNPP Packages

All ICSNPP Packages:

• ICSNPP

Full ICS Protocol Parsers:

• BACnet
  • Full Zeek protocol parser for BACnet (Building Control and Automation)
• BSAP
  • Full Zeek protocol parser for BSAP (Bristol Standard Asynchronous Protocol) over IP
  • Full Zeek protocol parser for BSAP Serial comm converted using serial tap device
• Ethercat
  • Full Zeek protocol parser for Ethercat
• Ethernet/IP and CIP
  • Full Zeek protocol parser for Ethernet/IP and CIP
• GE SRTP
  • Full Zeek protocol parser for GE SRTP
• Genisys
  • Full Zeek protocol parser for Genisys
• OPCUA-Binary
  • Full Zeek protocol parser for OPC UA (OPC Unified Architecture) - Binary
• S7Comm
  • Full Zeek protocol parser for S7comm, S7comm-plus, and COTP
• Synchrophasor
  • Full Zeek protocol parser for Synchrophasor Data Transfer for Power Systems (C37.118)
• Profinet IO CM
  • Full Zeek protocol parser for Profinet I/O Context Manager

Updates to Zeek ICS Protocol Parsers:

• DNP3
  • DNP3 Zeek script extending logging capabilities of Zeek's default DNP3 protocol parser
• Modbus
  • Modbus Zeek script extending logging capabilities of Zeek's default Modbus protocol parser

License

Copyright 2023 Battelle Energy Alliance, LLC. Released under the terms of the 3-Clause BSD License (see LICENSE.txt).