title: Beckhoff: Etherleak in TwinCAT RT network driver
description: Beckhoff's TwinCAT RT network driver for Intel 8254x and 8255x is providing EtherCAT functionality. The driver implements real-time features. Except for Ethernet frames sent from real-time functionality, all other Ethernet frames sent through the driver are not padded if their payload is less than the minimum Ethernet frame size. Instead, arbitrary memory content is transmitted within in the padding bytes of the frame. Most likely this memory contains slices from previously transmitted or received frames. By this method, memory content is disclosed, however, an attacker can hardly control which memory content is affected. For example, the disclosure can be provoked with small sized ICMP echo requests sent to the device.
problem types: CWE-459 Incomplete Cleanup
affected:
{
product: TwinCat Driver for Intel 8254x (Tcl8254x.sys)
vendor: Beckhoff
versions:
lessThanOrEqual: 3.1.0.3603 for TwinCAT 3.1 4024, status: affected, version: unspecified, versionType: custom
lessThanOrEqual: 3.1.0.3512 for TwinCAT 3.1 4022, status: affected, version: unspecified, versionType: custom
lessThanOrEqual: 2.11.0.2120 for TwinCAT 2.11 2350, status: affected, version: unspecified, versionType: custom
}
{
product: TwinCat Driver for Intel 8255x (Tcl8255x.sys)
vendor: Beckhoff
versions:
lessThanOrEqual: 3.1.0.3600 for TwinCAT 3.1 4024, status: affected, version: unspecified, versionType: custom
lessThanOrEqual: 3.1.0.3500 for TwinCAT 3.1 4024, status: affected, version: unspecified, versionType: custom
lessThanOrEqual: 2.11.0.2117 for TwinCAT 2.11 2350, status: affected, version: unspecified, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 5.3
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
version: 3.1
]
workarounds: If no real-time communication from TwinCAT is required on the Ethernet interface, then users can alternatively re-configure them to use the Intel ® driver, which is shipped with Beckhoff images.
Customers should configure a perimeter firewall to block traffic from untrusted networks to the device, especially regarding ICMP and other small ethernet frames.
Beckhoff offers software patches for TwinCAT 3.1 and TwinCAT 2.11 on request. These patches will be included in the the next regular releases to the affected software versions. The advisory will be updated upon availability.