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AUSCERT External Security Bulletin Redistribution
ESB-2019.4317
Advisory (icsa-19-318-01) Siemens Mentor Nucleus Networking Module
15 November 2019
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens Mentor Nucleus Networking Module
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Overwrite Arbitrary Files -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2019-13939
Original Bulletin:
https://www.us-cert.gov/ics/advisories/icsa-19-318-01
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ICS Advisory (ICSA-19-318-01)
Siemens Mentor Nucleus Networking Module
Original release date: November 14, 2019
Legal Notice
All information products included in http://ics-cert.us-cert.gov are
provided"as is" for informational purposes only. The Department of Homeland
Security (DHS) does not provide any warranties of any kind regarding any
information contained within. DHS does not endorse any commercial product or
service, referenced in this product or otherwise. Further dissemination of this
product is governed by the Traffic Light Protocol (TLP) marking in the header.
For more information about TLP, see http://www.us-cert.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.1
o ATTENTION: Low skill level to exploit
o Vendor: Siemens
o Equipment: Mentor Nucleus Networking Module
o Vulnerability: Improper Input Validation
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to affect
the integrity and availability of the device.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following networking modules from Mentor Nucleus (a division of Siemens)
are affected:
o Nucleus NET: All versions
o Nucleus RTOS: All versions
o Nucleus ReadyStart for ARM, MIPS, and PPC: All versions prior to v2017.02.2
with patch "Nucleus 2017.02.02 Nucleus NET Patch"
o Nucleus SafetyCert: All versions
o Nucleus Source Code: All versions
o VSTAR: All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER INPUT VALIDATION CWE-20
By sending specially crafted DHCP packets to a device, an attacker may be able
to affect availability and integrity of the device. Attackers require adjacent
network access to exploit this vulnerability, but do not require authentication
or user interaction.
CVE-2019-13939 has been assigned to this vulnerability. A CVSS v3 base score of
7.1 has been calculated; the CVSS vector string is ( AV:A/AC:L/PR:N/UI:N/S:U/
C:N/I:L/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Armis reported this vulnerability to Siemens.
4. MITIGATIONS
Siemens recommends installing the following software updates to address this
vulnerability.
Nucleus NET:
o Avoid using DHCP Client of Nucleus NET or upgrade Nucleus ReadyStart and
apply the corresponding patch.
Nucleus RTOS:
o Avoid using DHCP Client of Nucleus NET, or upgrade Nucleus ReadyStart and
apply the corresponding patch.
Nucleus ReadyStart for ARM, MIPS, and PPC:
o Upgrade to v2017.02.2 and install the patch "Nucleus 2017.02.02 Nucleus NET
Patch." Updated firmware versions can be obtained from Mentor supportcenter
at (login required):
https://support.mentor.com/en/product/1009925838/downloads
Nucleus SafetyCert:
o Nucleus SafetyCert is not affected since it leverages the LWNET stack,
which is not affected. The Nucleus SafetyCert bundle, however, does include
a copy of Nucleus ReadyStart to allow easier prototyping, which is
affected.
Nucleus Source Code:
o Avoid using DHCP Client of Nucleus NET.
VSTAR:
o Contact customer support to receive patch and update instructions.
As a general security measure, Siemens strongly recommends protecting network
access to devices with appropriate mechanisms. In order to operate the devices
in a protected IT environment, Siemens recommends configuring the environment
according to Siemens' Operational Guidelines for Industrial Security and to
follow the recommendations in the product manuals.
Additional information on Industrial Security by Siemens can be found at:
https://www.siemens.com/industrialsecurity
For more information on this vulnerability and more detailed mitigation
instructions, please see Siemens security advisory SSA-434032 at the following
location:
http://www.siemens.com/cert/advisories
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should
be updated to the most current version available. Also recognize that VPN
is only as secure as the connected devices.
CISA reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices
on the ICS webpage on us-cert.gov . Several recommended practices are available
for reading and download, including Improving Industrial Control Systems
Cybersecurity with Defense-in-Depth Strategies .
Additional mitigation guidance and recommended practices are publicly available
on the ICS webpage on us-cert.gov in the Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies .
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to CISA for tracking
and correlation against other incidents.
No known public exploits specifically target this vulnerability. This
vulnerability is not exploitable remotely.
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