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AUSCERT External Security Bulletin Redistribution
ESB-2016.2278
Siemens SCALANCE M-800/S615 Web Vulnerability
28 September 2016
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemen SCALANCE M-800 and S615 modules
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Access Confidential Data -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2016-7090
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-16-271-01
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Advisory (ICSA-16-271-01)
Siemens SCALANCE M-800/S615 Web Vulnerability
Original release date: September 27, 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
Siemens has identified a web security vulnerability in Siemen's SCALANCE
M-800 and S615 modules. This vulnerability was reported directly to Siemens
by Alexander Van Maele and Tijl Deneut from HOWEST. Siemens has produced
a new firmware version to mitigate this vulnerability.
AFFECTED PRODUCTS
Siemens reports that the vulnerability affects the following products:
SCALANCE M-800/S615: All versions before V4.02
IMPACT
Exploitation of this vulnerability could allow an attacker in a privileged
network position to obtain web session cookies under certain circumstances.
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 are SCALANCE M-800/S615 modules. SCALANCE M industrial
routers are industrial-grade routers used to connect networked industrial
components. This product line provides a Web interface to manage the
router configuration. The SCALANCE S firewall is used to protect trusted
industrial networks from untrusted networks and provides additional security
functionality, e.g., VPN tunnels==2E. According to Siemens, SCALANCE
M-800/S615 modules are deployed across several sectors including Chemical,
Critical Manufacturing, Dams, Defense Industrial Base, Energy, Food and
Agriculture, Government Facilities, Transportation Systems, and Water and
Wastewater Systems. Siemens estimates that these products are used worldwide.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
SENSITIVE COOKIE IN HTTPS SESSION WITHOUT "SECURE" ATTRIBUTE[a]
The integrated web server delivers session cookies without the "secure"
flag. Modern browsers interpreting the flag would mitigate potential data
leakage in case of clear text transmission.
CVE-2016-7090[b] has been assigned to this vulnerability. A CVSS
v3 base score of 4.0 has been calculated; the CVSS vector string is
(CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N).[c]
VULNERABILITY DETAILS
EXPLOITABILITY
This vulnerability could be exploited remotely.
EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
DIFFICULTY
Crafting a working exploit for this vulnerability would be difficult.
MITIGATION
Siemens provides firmware version V4.2 for SCALANCE M-800/S615 to mitigate
this vulnerability. The firmware version can be obtained here:
https://support.industry.siemens.com/cs/ww/en/view/109740858
Siemens strongly recommends users protect network access to the management
interface of SCALANCE M-800/S615 modules with appropriate mechanisms. Siemens
also advises that users configure the operational environment according
to Siemens overview of the operational guidelines for Industrial Security
(with the cell protection concept):
https://www.siemens.com/cert/operational-guidelines-industrial-security.
For more information on this vulnerability and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-342135 at the
following location:
http://www.siemens.com/cert/advisories
ICS-CERT recommends that users take defensive measures to minimize the
risk of exploitation of this vulnerability. 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 at:
http://ics-cert.us-cert.gov/content/recommended-practices. 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
(http://ics-cert.us-cert.gov/).
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-614: Sensitive Cookie in HTTPS Session Without 'Secure' Attribute,
https://cwe.mitre.org/data/definitions/614.html, web site last accessed
September 27, 2016.
b.
NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-7090,
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,
http://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:...,
web site last accessed September 27, 2016.
Contact Information
For any questions related to this report, please contact ICS-CERT at:
Email: ics-cert@hq.dhs.gov
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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