title: BECKHOFF: DoS-Vulnerability for TwinCAT OPC UA Server and IPC Diagnostics UA Server
description: TwinCAT OPC UA Server in versions up to 2.3.0.12 and IPC Diagnostics UA Server in versions up to 3.1.0.1 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.
problem types: CWE-20 Improper Input Validation
affected:
{
product: TwinCAT OPC UA Server
vendor: Beckhoff
versions:
lessThanOrEqual: 2.3.0.12, status: affected, version: unspecified, versionType: custom
}
{
product: IPC Diagnostics UA Server
vendor: Beckhoff
versions:
lessThanOrEqual: 3.1.0.1, status: affected, version: unspecified, versionType: custom
}
{
product: TF6100
vendor: Beckhoff
versions:
lessThanOrEqual: 3.3.18, status: affected, version: unspecified, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: LOW
baseScore: 5.3
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
version: 3.1
]
solutions: For devices running Windows but not Windows CE or TwinCAT/BSD please get a recent version of the OPC UA servers through the conventional ways and update your system.
For devices running Windows CE please request a recent image via Beckhoff’s support and apply it to your device.
For the product CX8091 please use firmware version "CX8091_CE600_LF_v356f_TC211R3_B2306_v2" or later.
Please note that the updated OPC UA server leaves less RAM available to your application on the CX8091.
workarounds: 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.