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AUSCERT External Security Bulletin Redistribution
ESB-2016.2495
Siemens SICAM RTU Devices Denial-of-Service Vulnerability
26 October 2016
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SICAM RTU
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2016-7987
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-16-299-01
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Advisory (ICSA-16-299-01)
Siemens SICAM RTU Devices Denial-of-Service Vulnerability
Original release date: October 25, 2016
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/.
OVERVIEW
Adam Crain of Automatak LLC has identified a denial-of-service vulnerability
in Siemens SICAM products. Siemens has produced a firmware update to mitigate
this vulnerability.
This vulnerability could be exploited remotely.
AFFECTED PRODUCTS
Siemens reports that the vulnerability affects the following versions of
SICAM:
ETA4 firmware (all versions prior to Revision 08) of the SM-2558 extension
module for:
SICAM AK,
SICAM TM 1703,
SICAM BC 1703, and
SICAM AK 3
ETA2 firmware (Revision 11.01 and earlier) of the SM-2556 extension module
for:
SICAM AK,
SICAM TM, and
SICAM BC.
IMPACT
Successful exploitation of this vulnerability could cause a denial of service.
A cold start might be required to recover the system.
Impact to individual organizations depends on many factors that are unique to
each organization. NCCIC/ICS-CERT recommends that organizations evaluate the
impact of this vulnerability based on their operational environment,
architecture, and product implementation.
BACKGROUND
Siemens is a multinational company headquartered in Munich, Germany.
The affected products, SM-2558 and SM-2556, are communication modules used to
connect networked industrial components. According to Siemens, SM-2558 and
SM-2556 communication modules are deployed across several sectors including
Chemical, Critical Manufacturing, Government Facilities, and others. Siemens
estimates that these products are used worldwide.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
DENIAL OF SERVICE[a]
Specially crafted packets sent to Port 2404/TCP could cause the affected
device to go into defect mode. A cold start might be required to recover the
system.
CVE-2016-7987[b] has been assigned to this vulnerability. A CVSS v3 base score
of 7.5 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).[c]
VULNERABILITY DETAILS
EXPLOITABILITY
This vulnerability could be exploited remotely.
EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
DIFFICULTY
An attacker with a low skill would be able to exploit this vulnerability.
MITIGATION
Siemens provides firmware ETA4 Revision 08 for SM-2558 that fixes the
vulnerability and recommends customers update to the fixed version.
http://w3.siemens.com/smartgrid/global/en/products-systems-solutions/substation-automation/substation-automation/Pages/Overview.aspx
(link is external)
For the SM-2556 extension module, Siemens recommends customers contact the
support center at: support.energy@siemens.com (link sends e-mail)
Until patches can be applied, Siemens advises to apply the following steps to
mitigate the risk:
Use a firewall or the IPsec functionality of the SM-2558 module to restrict
access to Port 2404/TCP
The SICAM RTUs ADMINISTRATOR Security Manual:
www.downloads.siemens.com/download-center/d/SIC_RTUs_ADMIN_SECURITY_ENG.pdf?mandator=ic_sg&segment=Global&fct=downloadasset&pos=download&id1=DLA05_43299
(link is external)
Always run RTUs in trusted networks.
As a general security measure Siemens strongly recommends to protect network
access with appropriate mechanisms (e.g., firewalls, segmentation, VPN). It is
advised to configure the environment according to Siemens operational
guidelines in order to run the devices in a protected IT environment.
Siemens recommends security guidelines to Secure Substation:
http://www.siemens.com/gridsecurity (link is external)
For more information on this vulnerability and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-296574 at the following
location:
http://www.siemens.com/cert/advisories (link is external)
ICS-CERT recommends that users take defensive measures to minimize the risk of
exploitation of these vulnerabilities. Specifically, users should:
Minimize network exposure for all control system devices and/or systems, and
ensure that they are not accessible from the Internet.
Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
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.
ICS-CERT reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
ICS-CERT 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 in the ICS-CERT Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies, that is available for download from the ICS-CERT web site.
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to ICS-CERT for
tracking and correlation against other incidents.
a. CWE-400: Uncontrolled Resource Consumption (Resource Exhaustion),
https://cwe.mitre.org/data/definitions/400.html, web site last accessed
October 25, 2016.
b. NVD, https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-7987, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
c. CVSS Calculator,
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S...,
web site last accessed October 25, 2016.
Contact Information
For any questions related to this report, please contact ICS-CERT at:
Email: ics-cert@hq.dhs.gov (link sends e-mail)
Toll Free: 1-877-776-7585
International Callers: (208) 526-0900
For industrial control systems security information and incident reporting:
http://ics-cert.us-cert.gov
ICS-CERT continuously strives to improve its products and services. You can
help by choosing one of the links below to provide feedback about this
product.
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