Modbus/TCP Discrete Input Access

Medium Nessus Plugin ID 23818


Discrete inputs from a Modicon field device, such as a PLC, RTU, or IED, can be read using function code 2.


Using 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.


Restrict access to the Modbus port (TCP/502) to authorized Modbus clients.

See Also

Plugin Details

Severity: Medium

ID: 23818

File Name: scada_modbus_di_check.nbin

Version: $Revision: 1.18 $

Type: remote

Family: SCADA

Published: 2006/12/11

Modified: 2016/10/18

Dependencies: 23817

Risk Information

Risk Factor: Medium


Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N

Vulnerability Information

Required KB Items: SCADA/modbus/coil