CVE-2020-12510

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.

• CWE-276
• CWE-276

• https://cert.vde.com/en-us/advisories/vde-2020-037Third Party Advisory
• https://cert.vde.com/en-us/advisories/vde-2020-037Third Party Advisory

Published

Nov 19, 2020

Last Modified

Jun 17, 2026

Status

Modified

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