It has been nearly three years since we last looked at the number of industrial devices (or, rather, devices that communicate with common OT protocols, such as Modbus/TCP, BACnet, etc.) that are accessible from the internet[1]. Back in May of 2021, I wrote a slightly optimistic diary mentioning that there were probably somewhere between 74.2 thousand (according to Censys) and 80.8 thousand (according to Shodan) such systems, and that based on long-term data from Shodan, it appeared as though there was a downward trend in the number of these systems.
Article Link: https://isc.sans.edu/diary/rss/30860