IEEE Consumer Electronics Magazine - May/June 2023 - 78

Analysis of Vulnerabilities
FIGURE 3. WemosD1-R2 crashes under DoS attack.
FIGURE 2. Arduino Mega not responding to neither
pings (up) nor web request (down) after an attack of
100 ICMP packets.
exception (see Figure 3). This happens in both
attacks: SYN flooding and HTTP DoS.
Yun Vulnerabilities-Arduino With OS
Hardware Analysis Arduino Yun board is an
interesting board to analyze due to its architecture
and operating mode. Yun is composed of two
well-defined modules: AVR ATmega32U4 microcontroller
and a MIPS Atheros AR9331 microprocessor.
The microcontroller runs Arduino code.
The processor runs a customized Linux distribution
based on OpenWrt called OpenWrt-Yun.
On the Arduino Yun, malicious parties with
hardware access could reset the board to its factory
values, what may lead to default configuration
vulnerabilities. Holding down the Arduino's
Wi-Fi reset button for more than 30 s will reset it
to factory conditions. If pressing down between
5 and 30 s, it will only reset the Wi-Fi settings.
Arduino Yun board does not have an integrated
voltage regulator unlike other Arduino
boards. Thanks to this integrated voltage regulator,
Arduino boards support a reduced range of
power input. However, Arduino Yun must be supplied
with a regulated 5 V dc power, so any higher
voltage will damage the board. Moreover, some
parts of the Arduino Yun board, like theWi-Fimodule,
are quite sensitive to unstable dc current.
Unstable currentmay reset or destroy theboard.40
Communication Analysis Arduino devices
can communicate with other devices using the
78
serial port. Arduino boards have at least one serial
interface, while Yun boards have two: Serial and
Serial1.41 Serial is used to communicate with an
external device. Serial1 interface is reserved to
board internal communication; it has the 0 (RX)
and 1(TX) external pins, where any person with
physical access to the devices could connect.
However, OpenWrt sets the communication baudrate
to 250,000,42 which is not commonly supported
by serial clients because of the difficulty to
handle errors using that speed. If an attacker gains
access to the Arduino boards and he is able to
read on 250 Kbauds, he may use two serial cables
to read from RX and TX and see data exchange
between microprocessor and microcontroller,
since the communication is nonencrypted.
YUN-based network devices use Linux (see
Figure 4). Thus, there are potentially more hardware
resources and powerful software to perform
network management. As in any other
Linux device, many tools can be installed in
order to manage the network, such as IPTables
and Snort. IPTables is generally used as a firewall
because it provides packet filtering, network
address translation, and other packet advance
management. Snort is a real-time traffic analysis
and packet logger that can be used as Intrusion
Prevention System (IDS).
Regarding DoS and SYN attacks, Arduino YUN
boards through Wi-Fi tolerate both SYN flooding
and HTTP DoS attacks. While these attacks are
being performed, the access to the server
becomes almost impossible. However, once
attacks stop, the server becomes accessible
again with no need to restart the board.
Figure 5 shows the YUN board response time
to pings while performing the DoS attack. The
chart shows that for some seconds, the response
time increases but finally Linux can handle it and
recovers its normal response timing.
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IEEE Consumer Electronics Magazine - May/June 2023

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