Rockwell Patches RSLinx Classic Bug

Friday, May 8, 2015 @ 11:05 AM gHale

Rockwell Automation created a new version that mitigates a stack-based buffer overflow vulnerability in its OPCTest.exe, which is a test client for RSLinx Classic’s support of the OPC-DA protocol, according to a report on ICS-CERT.

RSLinx Classic, all versions prior to Version 3.73.00 suffers from the issue, discovered by Ivan Sanchez of WiseSecurity Team.

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Successful exploitation of this vulnerability could result in the application crashing or allow malicious code injection.

Rockwell Automation, based in Milwaukee, WI, provides industrial automation control and information products worldwide across a wide range of industries.

The affected product, RSLinx Classic, enables communications for a variety of Rockwell Software applications used in industrial control systems. The software sees action across several sectors including critical manufacturing, energy, water and wastewater systems, and others. Rockwell Automation said they deploy the product globally.

Social engineering is mandatory to convince a user to introduce and load a uniquely crafted CSV file that could cause a buffer overflow that may allow an attacker to crash the application, requiring a restart, or to execute malicious code with the same or higher privileges as the authenticated user.

CVE-2014-9204 is the case number assigned to this vulnerability, which has a CVSS v2 base score of 5.9.

This vulnerability is not exploitable remotely and cannot end up exploited without user interaction. The exploit only triggers when a local user runs the vulnerable application and loads the malformed CSV file.

No known public exploits specifically target this vulnerability. Crafting a working exploit for this vulnerability would be difficult. Social engineering would have to come into play to convince the user to accept the malicious file. Additional user interaction would have to load the malformed CSV file. This decreases the likelihood of a successful exploit.

Rockwell produced a new version, Version 3.73, for RSLinx Classic that includes a new version of OPCTest.exe that mitigates the buffer overflow vulnerability.

Rockwell Automation encourages asset owners using the affected software to upgrade to the newest available software version. Rockwell recommends asset owners implement additional precautions and risk mitigation strategies, when possible, to enhance resilience against similar attacks:
• Do not open untrusted CSV files with OPCTest.exe
• Limit access to those assets using RSLinx Classic and other software to authorized personnel
• Run all software as User and not as an Administrator
• Restrict network access to assets with RSLinx Classic and other software, as appropriate
• Interact with, and only obtain software and software patches from trustworthy highly reputable sources
• Use Whitelisting applications to help mitigate risk
• Follow good network design practices that include network separation and segmentation; use DMZs with properly configured firewalls to selectively control and monitor traffic passed between zones and systems
• Maintain layered physical and logical security to implement defense-in-depth design practices for the ICS
• Reaffirm with employees the importance for constant vigilance, especially in regard to the ongoing potential for social engineering attacks to manipulate otherwise normal user behaviors

Rockwell’s disclosure contains the link to its software download page.

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