ICSNPP-BSAP

Industrial Control Systems Network Protocol Parsers (ICSNPP) - BSAP over IP.

Overview

ICSNPP-BSAP is a Zeek plugin for parsing and logging fields within the BSAP (Bristol Standard Asynchronous Protocol).

This plugin was developed to be fully customizable. To drill down into specific BSAP packets and log certain variables, users can add the logging functionality to scripts/icsnpp/bsap/main.zeek. The functions within scripts/icsnpp/bsap/main.zeek and src/events.bif are good guides for adding new logging functionality.

This parser produces seven log files. These log files are defined in scripts/icsnpp/bsap/main.zeek.

• bsap_ip_header.log
• bsap_ip_rdb.log
• bsap_ip_unknown.log
• bsap_serial_header.log
• bsap_serial_rdb.log
• bsap_serial_rdb_ext.log
• bsap_serial_unknown.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-bsap

If this package is installed from ZKG, it will be added to the available plugins. This can be tested by running zeek -N. If installed correctly, users will see ICSNPP::BSAP.

If ZKG is configured to load packages (see @load packages in quickstart guide), this plugin and these scripts 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 package on a packet capture, they can add icsnpp/bsap to the command to run this plugin's scripts on the packet capture:

git clone https://github.com/cisagov/icsnpp-bsap.git
zeek -Cr icsnpp-bsap/tests/traces/bsap-ip_example.pcap icsnpp/bsap
zeek -Cr icsnpp-bsap/tests/traces/bsap-serial_example.pcapng icsnpp/bsap

Manual Install

To install this package manually, clone this repository and run the configure and make commands as shown below.

git clone https://github.com/cisagov/icsnpp-bsap.git
cd icsnpp-bsap/
./configure
make

If these commands succeed, users will end up with a newly created build directory that contains all the files needed to run/test this plugin. The easiest way to test the parser is to point the ZEEK_PLUGIN_PATH environment variable to this build directory.

export ZEEK_PLUGIN_PATH=$PWD/build/
zeek -N # Ensure everything compiled correctly and you are able to see ICSNPP::BSAP_IP

Once users have tested the functionality locally and it appears to have compiled correctly, they can install it system-wide:

sudo make install
unset ZEEK_PLUGIN_PATH
zeek -N # Ensure everything installed correctly and you are able to see ICSNPP::BSAP_IP

To run this plugin in a site deployment users will need to add the line @load icsnpp/bsap to the site/local.zeek file to load this plugin's scripts.

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/bsap to the command to run this plugin's scripts on the packet capture:

zeek -Cr icsnpp-bsap/tests/traces/bsap-ip_example.pcap icsnpp/bsap
zeek -Cr icsnpp-bsap/tests/traces/bsap-serial_example.pcapng icsnpp/bsap

If users want to deploy this plugin on an already existing Zeek implementation and don't want to build the plugin on the machine, they can extract the ICSNPP_Bsap.tgz file to the directory of the established ZEEK_PLUGIN_PATH (default is ${ZEEK_INSTALLATION_DIR}/lib/zeek/plugins/).

tar xvzf build/ICSNPP_Bsap.tgz -C $ZEEK_PLUGIN_PATH 

Logging Capabilities

Header Log (bsap_ip_header.log)

Overview

This log captures BSAP header information for every BSAP packet converted to ethernet and logs it to bsap_ip_header.log.

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)
num_msg	string	Number of functions per message
type_name	count	Message type

RDB (Remote Database Access) Log (bsap_ip_rdb.log)

Overview

This log captures BSAP RDB function information and logs it to bsap_ip_rdb.log.

The vast majority of BSAP traffic is RDB function traffic. The RDB access is used to read and write variables between master and slave RTUs.

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)
header_size	count	Header length
mes_seq	count	Message sequence
res_seq	count	Response sequence
data_len	count	Length of data
sequence	count	Function sequence (same as response)
app_func_code	string	Application function
node_status	count	Node status byte
func_code	string	Application sub function
variable_count	count	Variable count in message
variables	vector	Vector of variables in message
variable_value	vector	Vector of variable value in message

Unknown Log (bsap_ip_unknown.log)

Overview

This log captures all other zeek_bsap_ip traffic that hasn't been defined and logs it to bsap_ip_unknown.log.

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)
data	string	BSAP_IP unknown data

BSAP Header Log (bsap_serial_header.log)

Overview

This log captures BSAP header information for every BSAP packet converted to Ethernet and logs it to bsap_serial_header.log.

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)
ser	string	Message serial number
dadd	count	Destination address
sadd	count	Source address
ctl	count	Control byte
dfun	string	Destination function
seq	count	Message sequence
sfun	string	Source function
nsb	count	Node status byte
type_name	string	Local or global header

BSAP RDB (Remote Database Access) Log (bsap_serial_rdb.log)

Overview

This log captures BSAP RDB function information and logs it to bsap_serial_rdb.log.

The vast majority of BSAP traffic is RDB function traffic. The RDB access is used to read and write variables between master and slave RTU's.

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)
func_code	string	RDB function being initiated
variables	vector	Vector of variables in message
variable_value	vector	Vector of variable value in message

BSAP BSAP_RDB_EXT (Remote Database Access Extended) Log (bsap_serial_rdb_ext.log)

Overview

This log captures BSAP RDB Extension function information and logs it to bsap_serial_rdb_ext.log.

These Extension functions of RDB contain information from controllers loading date and time, setting clearing diagnostics, and calling system resets. These only pertain to the GFC 3308 controllers.

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)
dfun	string	Destination function
seq	count	Message sequence
sfun	string	Source function
nsb	count	Node status byte
extfun	string	RDB extension function
data	string	RDB extension function specific data

BSAP Unknown (bsap_serial_unknown.log)

Overview

This log captures all other BSAP traffic that hasn't been defined and logs it to bsap_serial_unknown.log.

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)
data	string	BSAP unknown data

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.

General/Header Logging

The general BSAP log files (bsap_ip_header.log and bsap_serial_header.log) contains basic header information for all known (~100%) BSAP IP and Serial messages, but provide very little detailed information about the messages.

Detailed Logging

Detailed logging for BSAP RDB messages are logged in the RDB log files (bsap_ip_rdb.log, bsap_serial_rdb.log, and bsap_serial_rdb_ext.log). These logs contain ~90% logged data for BSAP RDB messages which are the most common BSAP message type.

Non-BSAP RDB messages which commonly account for <10% of BSAP traffic do not contain detailed logging, however, raw data from these other messages are logged in the unknown log files (bsap_ip_unknown.log and bsap_serial_unknown.log).

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).