Siemens works to fix vulnerability in critical control networks

Remotely exploitable flaw could disrupt devices used by utilities, refineries others

Siemens is working on a fix for a remotely exploitable vulnerability in network routers and switches from subsidiary RuggedCom that are widely deployed in refineries, power substations and other critical infrastructure networks in the U.S.

In a statement, Siemens said it was notified of the issue by the Department of Homeland Security's Industrial Control Systems Computer Emergency Response Team (ICS-CERT) earlier this week. The vulnerability stems from a hard-coded RSA SSL private key in RuggedCom's Rugged Operating System (ROS) that gives attackers a way to decrypt traffic between an end user and the router.

According to ICS-CERT, the hard-coded key can be used by attackers to launch malicious communications against RuggedCom network devices.

"Specialists from Siemens and RuggedCom are investigating this issue and will provide information updates as soon as they become available," the company said, without specifying when that might happen. Siemens acquired RuggedCom earlier this year.

ICS-CERT on Wednesday issued an alert warning operators of industrial control networks about the problem. The alert urged administrators to ensure that control system devices are not connected directly to the Internet and to make sure all control system networks and devices are behind firewalls.

"If remote access is required, employ secure methods, such as Virtual Private Networks (VPNs), recognizing that VPN is only as secure as the connected devices," ICS-CERT warned.

The vulnerability with proof-of-concept code was publicly disclosed at a security conference last week by Justin Clarke, a security researcher at Cylance Inc. It was that disclosure that prompted the ICS-CERT alert and Siemens' effort to find a fix.

Dale Peterson, CEO of Digital Bond, a consulting firm specializing in control system security, said the flaw allows an attacker to access the login credentials to RuggedCom devices and to launch denial-of-service attacks against network devices running the vulnerable OS.

Peterson described RuggedCom as the "Cisco" of the industrial control network space and said the company is the largest supplier of ruggedized network devices to industrial control systems owners in the U.S.

The vulnerability described by Clarke is akin to flaws in older versions of Microsoft's Remote Desktop Protocol clients and Terminal Servers. And just like Microsoft, it will likely take Siemens a while to address the issue, he said.

By itself, the vulnerability is unlikely to greatly heighten risks for operators of industrial control networks, according to Peterson. That's because an attacker would already need to have access to an ICS network to be able to exploit the vulnerability. "It's pretty much game over if you already have someone on your network," he said. "This [vulnerability] gives them just another thing they can do as an attacker."

Even so, flaws such as this highlight the fundamental security problems that exist in systems running critical infrastructure equipment and networks, he said.

This is the second security vulnerability in RuggedCom's products in just the past few months, Peterson noted. "They had a terrible response last time, so it will be interesting to see if they do better with this one," he said. In addition to fixing the issue, RuggedCom also needs to offer an explanation to customers about how it plans on changing its software development and testing processes to ensure such problems don't continue, he said.

Security vulnerabilities in critical infrastructure networks have been gaining attention from security researchers in recent years -- especially after Stuxnet. In the past two years, the number of flaws discovered in ICS and SCADA systems has gone up by nearly 400% Peterson said.

The heightened attention is pushing vendors to address security issues more aggressively. However, a lot of vendors still don't act until someone publicly discloses a flaw in their products, he added.

Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan or subscribe to Jaikumar's RSS feed. His e-mail address is

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Copyright © 2012 IDG Communications, Inc.

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