-----BEGIN PGP SIGNED MESSAGE-----
AUSCERT External Security Bulletin Redistribution
Advisory (icsa-19-318-01) Siemens Mentor Nucleus Networking Module
15 November 2019
AusCERT Security Bulletin Summary
Product: Siemens Mentor Nucleus Networking Module
Operating System: Network Appliance
Impact/Access: Overwrite Arbitrary Files -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2019-13939
- --------------------------BEGIN INCLUDED TEXT--------------------
ICS Advisory (ICSA-19-318-01)
Siemens Mentor Nucleus Networking Module
Original release date: November 14, 2019
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)
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/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
Armis reported this vulnerability to Siemens.
Siemens recommends installing the following software updates to address this
o Avoid using DHCP Client of Nucleus NET or upgrade Nucleus ReadyStart and
apply the corresponding patch.
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):
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
Nucleus Source Code:
o Avoid using DHCP Client of Nucleus NET.
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:
For more information on this vulnerability and more detailed mitigation
instructions, please see Siemens security advisory SSA-434032 at the following
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
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.
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to firstname.lastname@example.org
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
Australian Computer Emergency Response Team
The University of Queensland
Internet Email: email@example.com
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
-----BEGIN PGP SIGNATURE-----
-----END PGP SIGNATURE-----