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AUSCERT External Security Bulletin Redistribution
ESB-2019.1010.2
Siemens SCALANCE X
27 March 2019
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SCALANCE X
Publisher: US-CERT
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Access Confidential Data -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2019-6569
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-19-085-01
Revision History: March 27 2019: updated product tag
March 27 2019: Initial Release
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Advisory (ICSA-19-085-01)
Siemens SCALANCE X
Original release date: March 26, 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 5.4
o ATTENTION: Exploitable remotely
o Vendor: Siemens
o Equipment: SCALANCE X
o Vulnerability: Expected Behavior Violation
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to feed
data over a mirror port and into the mirrored network.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following SCALANCE products are affected:
o SCALANCE X-200, all versions;
o SCALANCE X-300, all versions; and
o SCALANCE XP/XC/XF-200, all versions older than v4.1
3.2 VULNERABILITY OVERVIEW
3.2.1 EXPECTED BEHAVIOR VIOLATION CWE-440
The monitor barrier of the affected products insufficiently blocks data from
being forwarded over the mirror port and into the mirrored network. An attacker
could exploit this vulnerability to transmit malicious packets to systems in
the mirrored network to influence their configuration and runtime behavior.
This vulnerability could be exploited by an attacker with network access to the
traffic-receiving network. Successful exploitation requires no system
privileges and no user interaction. An attacker could use the vulnerability to
compromise the confidentiality and availability of the traffic-generating
network.
CVE-2019-6569 has been assigned to this vulnerability. A CVSS v3 base score of
5.4 has been calculated; the CVSS vector string is ( AV:N/AC:H/PR:N/UI:N/S:C/
C:L/I:N/A:L ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Energy,
Food and Agriculture, and Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Siemens reported this vulnerability to NCCIC.
4. MITIGATIONS
Siemens has identified the following specific workaround/mitigation that users
can implement to reduce the risk associated with this vulnerability in SCALANCE
XP/XC/XF-200:
o Update to v4.1: https://support.industry.siemens.com/cs/ww/en/view/
109762982
Until a software update can be installed, Siemens recommends users apply
defense in depth principles, particularly ensuring that no devices that
transmit data back in the mirroring network are operated within the mirrored
network.
As a general security measure, Siemens strongly recommends users protect
network access to devices with appropriate mechanisms. To operate devices in a
protected IT environment, Siemens recommends configuring the environment
according to Siemens' operational guidelines for industrial security ( https://
www.siemens.com/cert/operational-guidelines-industrial-security ), and
following the product manual recommendations.
Additional information on industrial security by Siemens is available at:
https://www.siemens.com/industrialsecurity
For additional information see Siemens' security advisory SSA-557804 at the
following location:
http://www.siemens.com/cert/en/cert-security-advisories.htm
NCCIC 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.
NCCIC reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
NCCIC also provides a section for control systems security recommended
practices on the ICS-CERT web page. 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-CERT website 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 NCCIC for tracking
and correlation against other incidents.
This vulnerability requires high skill level to exploit. No known public
exploits specifically target this vulnerability.
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