CVE-2020-12510 Information

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.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

Reference

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

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

REQUIRED

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.3