ICS Advisories

Risk evaluation

Some TwinCAT OPC UA Server and IPC Diagnostics UA Server versions from Beckhoff Automation GmbH & Co. KG are vulnerable to denial of service attacks. The attacker needs to send several specifically crafted requests to the running OPC UA server. After some of these requests the OPC UA server is no longer responsive to any client. This is without effect to the real-time functionality of IPCs. UPDATE A - 11.05.2021 Please note that some hardware products from Beckhoff are shipped with a TwinCAT OPC UA Server pre-installed. In some cases the server is enabled by default. IPC Diagnostics UA Server (contained in Beckhoff's Windows images) server versions up to and including 3.1.0.1 are affected Please note that IPC products from Beckhoff are shipped with an IPC Diagnostics UA Server pre-installed. In all cases the server is disabled by default. The version numbers named above always refer to the version number which is accessible via OPC UA at the server via the standard OPC UA node /Objects/Server/ServerStatus/BuildInfo/SoftwareVersion and on Windows also as the file property "File version" of the file TcOpcUaServer.exe for TwinCAT OPC UA Server respectively the file DevMgrSvr-UA.exe for IPC Diagnostics UA Server. UPDATE A - 11.05.2021 Please note that IPC products from Beckhoff are shipped with an IPC Diagnostics UA Server pre-installed. While on Windows CE it is disabled by default all other Windows images have it enabled by default.

Mitigation summary

Consider disabling the IPC Diagnostics Server by stopping and disabling the corresponding Windows service or service. For example this can be achieved with the following PowerShell commands: Stop-Service -Force -Name DevMgrSvr-UA Set-Service -Name DevMgrSvr-UA -StartupType Disabled Alternatively consider limiting access to the TCP port the OPC UA server is listening on. This can happen with a dedicated firewall appliance which sits in front of an affected device. Alternatively at the device the Windows firewall can be configured to limit access to the TCP port. Further guidance is provided within the "Security Guide IPC" from Beckhoff which is accessible at https://www.beckhoff.com/secguide