Chemical Engineering September 2018 - 45

Engineering Practice
Protecting Sensor Data Transmitted
Wirelessly: A Grounds-Up Approach
Do not assume security is extensive enough to protect your critical data and
processes. Take a layered security approach using different tactics to establish best
practices for protecting network data
Josh Schadel,
SignalFire Wireless Telemetry
A
lmost daily, the headlines
tout the latest data breach
that puts company proprietary
information in jeopardy.
To avoid such situations, many enterprises
enforce different security measures
to protect data from known
and unknown risks. In addition to
protecting information stored in the
corporate infrastructure, businesses
must also consider the data transmitted
over any network. Attacks on
wireless sensor and control networks
can result in lost data and unintended
system operations that cause production
loss or safety issues.
Even information that seems to
pose little risk if not secured can
impact operations. A simple tank
level reading may, by itself, seem
unnecessary to protect. However, if
an outsider tampers with data and
changes the values, a false reading
could shut down operations or even
cause a spill. Therefore, both sensor
readings and commands must
remain valid. For example, a bogus
" high " tank level alert sent by an attacker
could trigger a production
shutdown. Conversely, an erroneous
" low " tank level warning could lead
to tank overflow and spill.
As wireless sensing and control
networks are more prominently used
to monitor and control a wide range
of assets in industries as diverse as oil
and gas, agriculture, water treatment,
food processing and transportation,
network security is essential to ensure
the authenticity, confidentiality and integrity
of data as they pass from device
to device. Using different security
measures, companies can ensure
data are only read by the intended
recipient and remain valid without any
content modification from the point
44
Nodes
FIGURE 1. Security checks must protect sensor data as they passes through the wireless remote monitoring
and control system. Using data without an integrity check is risky as it can cause unknown actions
of transmission to the point of reception.
To validate sensor data passing
through different transmission points,
layers of protection must safeguard
data packets from malicious attackers
who could steal and change the
contents. While wirelessly transmitting
data without integrity checks is
risky, many companies still do not
implement security protocols to protect
their network data.
Transmitting data wirelessly
Figure 1 outlines a standard configuration
of a wireless asset monitoringand-control
system. Nodes extract,
and transmit data from sensors via
radio transmission to a gateway that
serves as the central hub to serve
data to a variety of applications. A
wireless sensor network can concurrently
monitor different assets from a
variety of sensors in one network.
For example, in the upstream oiland-gas
market, measurements of
level, temperature, vibration, pressure,
flow and other parameters
can be tied into one network. The
gateway of such a network formats
sensor data per industry standards
(like Modbus) so that programmable
logic controllers (PLCs), distributed
control systems (DCS), supervisory
control and data acquisition systems
(SCADA) can process the data. The
information is delivered and integrated
over a wired digital protocol
like Modbus serial (RS485), Modbus
over Ethernet (Modbus TCP), Ethernet
IP or wirelessly using cell modems
or satellite communications.
More than automating data collection,
these wireless telemetry systems
are capable of managing assets
" over the air " (sending an alert
that controls a valve), eliminating the
use of expensive cabling. Furthermore,
the collected data are downloadable
into analytics software for
asset condition monitoring and predictive
diagnostics.
One wireless sensor monitoringand-control
system can employ
gateways that accommodate hundreds
of transceiver nodes spread
out over many square miles. Because
of the wide geographic range
of the network and critical nature of
the processing facilities, security is
a must to protect against potential
breaches as data pass from point to
point. The first line of defense is the
sensor network as it packages the
data. The second line of defense is
the hub (that is, the gateway), where
data are served to applications.
Types of data threats
Different types of data intrusions can
interrupt a wireless sensor network or
create some vulnerability, jeopardizing
the reliability and integrity of information
moving bi-directionally over
the wireless network. A breach of the
data moving to and from an asset
could cause a problem with the plant
or process operations. One common
threat or technique to breach a digital
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