OMRON has released the following countermeasures for users to implement:

Enable the hardware switch to prohibit writing UM (DIP switch on front panel of the CPU Unit)
Set UM read protection password and “Prohibit from overwriting to a protected program “option.

If the countermeasures cannot be applied, OMRON recommends that customers take the following mitigation measures:

Security measures to prevent unauthorized access:

If the following products and versions are used, the risk of attacks by an attacker via the network can be reduced by taking the following measures.
- Enable the FINS write protection function.
- Select the Protect by IP Address
Minimize connection of control systems and equipment to open networks, so that untrusted devices will be unable to access them.
Implement firewalls (by shutting down unused communications ports, limiting communications hosts, limiting access to FINS port (9600)) and isolate them from the IT network.
Use a virtual private network (VPN) for remote access to control systems and equipment.
Use strong passwords and change them frequently.
Install physical controls so that only authorized personnel can access control systems and equipment.
Scan virus to ensure safety of any USB drives or similar devices before connecting them to systems and devices.
Enforce multifactor authentication to all devices with remote access to control systems and equipment whenever possible.
Anti-virus protection
- Protect any PC with access to the control system against malware and ensure installation and maintenance of up-to-date commercial grade anti-virus software protection.
Data input and output protection
- Validation processing such as backup and range check to cope with unintentional modification of input/output data to control systems and devices.
Data recovery
- Periodical data backup and maintenance to prepare for data loss.

For more information, see Omron’s Security Advisory.

CJ1M SYSMAC CS-series Security Vulnerabilities