New RuggedCom Hole Already Fixed

Thursday, October 29, 2015 @ 11:10 AM gHale

A newly discovered vulnerability in an older version of Siemens RuggedCom ended up fixed in a newer version that fixed other vulnerabilities.

While that may sound confusing, it really isn’t. As it turns out, David Formby and Raheem Beyah of Georgia Tech have identified a vulnerability caused by an Institute of Electrical and Electronics Engineers (IEEE) conformance issue involving improper frame padding in Siemens RuggedCom.

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While that discovery is new, Siemens had already released a revision that eliminated the vulnerability. ICS-CERT released an advisory to serve as a notification of a discovery of a new vulnerability in the previous software version. Just to make sure, the researchers tested the revision to validate that it resolves the reported vulnerability.

The vulnerability affected all versions of ROS prior to 4.2.1

IEEE 802 specifies that packets have a minimum size of 56 bytes. The Ethernet driver should fill the data field with octets of zero for padding when packets are less than 56 bytes. Resident memory and other data end up used for padding in some implementations that could cause information leakage. This attack is passive; the attacker can only see data the affected device sent out as part of a packet.

Siemens’ headquarters is in Munich, Germany.

The affected products, Siemens RuggedCom ROS and ROX-based devices, connect devices that operate in harsh environments such as electric utility substations and traffic control cabinets. RuggedCom ROS and ROX-based devices see action across several sectors including energy, healthcare and public health, and transportation systems. Siemens estimates these products see use worldwide.

The data padding within the data field of the Ethernet pack should be all zeros. The previous implementation of firmware allowed other data from a known area of memory to end up used in this field and could exfiltrate or leak data.

CVE-2015-7836 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 4.3.

The attacker would need to be the receiver of the packet (that contains leaked data) or along the path (e.g., on a local network that does not use encryption).

There are no known exploits that target this vulnerability. An attacker with a low skill would be able to exploit this vulnerability. This is a passive attack; the attacker can only access the data that are contained within the packet.

Siemens released firmware update v4.2.1 for ROS-based devices which fixes the vulnerability. The firmware updates for the affected products are available by contacting Siemens by one of the following methods:
• Submit a support request online
• Call a local hotline center

For more information on this vulnerability and more detailed mitigation instructions, please see Siemens Security Advisory SSA-921524.