Beckhoff Twincat Incorrect Default Permissions

high Tenable.ot Plugin ID 500434
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Description

The default installation path of the TwinCAT XAR 3.1 software in all versions is underneath C:\TwinCAT. If the directory does not exist it and further subdirectories are created with permissions which allow every local user to modify the content. The default installation registers TcSysUI.exe for automatic execution upon log in of a user. If a less privileged user has a local account he or she can replace TcSysUI.exe. It will be executed automatically by another user during login. This is also true for users with administrative access. Consequently, a less privileged user can trick a higher privileged user into executing code he or she modified this way. By default Beckhoff’s IPCs are shipped with TwinCAT software installed this way and with just a single local user configured. Thus the vulnerability exists if further less privileged users have been added.

Solution

Refer to vendor advisory for Security Updates

See Also

https://cert.vde.com/en-us/advisories/vde-2020-037

Plugin Details

Severity: High

ID: 500434

Version: 1.0

Type: local

Family: SCADA

Published: 8/10/2021

Updated: 8/10/2021

Risk Information

CVSS Score Source: CVE-2020-12510

CVSS v2

Risk Factor: Medium

Base Score: 6

Vector: AV:N/AC:M/Au:S/C:P/I:P/A:P

CVSS v3

Risk Factor: High

Base Score: 7.3

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

Vulnerability Information

CPE: cpe:2.3:a:beckhoff:twincat_extended_automation_runtime:3.1:*:*:*:*:*:*:*

Patch Publication Date: 11/19/2020

Vulnerability Publication Date: 11/19/2020

Reference Information

CVE: CVE-2020-12510