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Rockwell Automation RSLinx Classic and FactoryTalk Linx Gateway Privilege Escalation

Medium
Advisory ID
ZSL-2018-5473
Release Date
10 June 2018
Vendor
Rockwell Automation, Inc. - https://www.rockwellautomation.com
Affected Version
Rockwell Automation RSLinx Classic 3.90.01, Rockwell Automation RSLinx Classic 3.73.00, Rockwell Automation RSLinx Classic 3.72.00, Rockwell Automation RSLinx Classic 2.58.00, Rockwell Automation FactoryTalk Linx Gateway 3.90.00
Tested On
Microsoft Windows 7 Professional SP1 (EN)
Summary

RSLinx Classic is a software platform that allows Logix5000 Programmable Automation Controllers to connect to a wide variety of Rockwell Software applications, and FactoryTalk Linx Gateway is a software that provides an Open Platform Communications (OPC) Unified Architecture (UA) server interface to allow the delivery of information from Rockwell Software applications to Allen-Bradley controllers.

Description

The application suffers from an unquoted search path issue impacting the service 'dnwhodisp' for Windows deployed as part of RSLinx and FactoryTalk. This could potentially allow an authorized but non-privileged local user to execute arbitrary code with elevated privileges on the system. A successful attempt would require the local user to be able to insert their code in the system root path undetected by the OS or other security applications where it could potentially be executed during application startup or reboot. If successful, the local user's code would execute with the elevated privileges of the application.

Proof of Concept
Disclosure Timeline
11.12.2017Vulnerability discovered.
11.12.2017Vendor contacted.
11.12.2017Vendor responds asking more details, providing PGP key.
11.12.2017Sent details to the vendor.
19.12.2017Asked vendor for status update.
20.12.2017Vendor is investigating the issue.
27.02.2018Asked vendor for status update.
27.02.2018Vendor verifies the issues, working on a fix.
13.03.2018Asked vendor for status update.
04.06.2018Vendor replies with release information. Provides fixed version RSLinx Classic 4.00.01 and FactoryTalk Linx Gateway 6.00.00 to its customers.
06.06.2018Vendor sends draft advisory to ZSL.
07.06.2018Replied to the vendor.
10.06.2018Coordinated public security advisory released.
Credits
Vulnerability discovered by Gjoko Krstic
References
Changelog
10.06.2018Initial release
22.06.2018Added reference [6], [7], [8], [9] and [10]
31.01.2024Added reference [11]