Modbus/TCP Discrete Input Access
Medium Nessus Plugin ID 23818
SynopsisDiscrete inputs from a Modicon field device, such as a PLC, RTU, or IED, can be read using function code 2.
DescriptionUsing function code 2, Modbus can read the discrete inputs from a Modbus slave, which is commonly used by SCADA and DCS field devices.
Discrete inputs represent binary (i.e boolean) values that often map to switches, relays, or other sensors. A sample of discrete inputs read from the device are provided by the plugin output.
The ability to read discrete inputs may help an attacker profile a system.
SolutionRestrict access to the Modbus port (TCP/502) to authorized Modbus clients.