  The ongoing trend to move industrial appliances from previously isolated
networks to the Internet requires fundamental changes in security to uphold
secure and safe operation. Consequently, to ensure end-to-end secure
communication and authentication, (i) traditional industrial protocols, e.g.,
Modbus, are retrofitted with TLS support, and (ii) modern protocols, e.g.,
MQTT, are directly designed to use TLS. To understand whether these changes
indeed lead to secure Industrial Internet of Things deployments, i.e., using
TLS-based protocols, which are configured according to security best practices,
we perform an Internet-wide security assessment of ten industrial protocols
covering the complete IPv4 address space.
  Our results show that both, retrofitted existing protocols and newly
developed secure alternatives, are barely noticeable in the wild. While we find
that new protocols have a higher TLS adoption rate than traditional protocols
(7.2% vs. 0.4%), the overall adoption of TLS is comparably low (6.5% of hosts).
Thus, most industrial deployments (934,736 hosts) are insecurely connected to
the Internet. Furthermore, we identify that 42% of hosts with TLS support
(26,665 hosts) show security deficits, e.g., missing access control. Finally,
we show that support in configuring systems securely, e.g., via configuration
templates, is promising to strengthen security.
