Vulnerability · Published Nov 19, 2020 · Assigned by CERTVDE
CVE-2020-12510Beckhoff: Privilege Escalation through TwinCat System
High 7.3
In plain English
A high-severity incorrect default permissions in TwinCat XAR 3.1 from Beckhoff. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 59% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Beckhoff | TwinCat XAR 3.1 | all |
Weakness: CWE-276 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
References
- https://cert.vde.com/en-us/advisories/vde-2020-037 x_refsource_CONFIRM