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AUSCERT External Security Bulletin Redistribution
Advisory (ICSA-17-332-01) Siemens SCALANCE W1750D, M800, and S615
29 November 2017
AusCERT Security Bulletin Summary
Product: Siemens SCALANCE
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2017-14496 CVE-2017-14495 CVE-2017-14491
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Siemens SCALANCE W1750D, M800, and S615
Original release date: November 28, 2017
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CVSS v3 8.1
ATTENTION: Remotely exploitable/low skill level to exploit.
Equipment: SCALANCE W1750D, M800, and S615
Vulnerabilities: Resource Exhaustion, Improper Restriction of Operations
within the Bounds of a Memory Buffer
The following versions of SCALANCE, network interfaces, are affected:
SCALANCE W1750D: All versions, and
SCALANCE M800/S615: All versions.
Successful exploitation of these vulnerabilities could allow a remote attacker
to crash the DNS service or execute arbitrary code by crafting malicious DNS
Siemens reports they are preparing updates for the affected products and
recommends the following mitigations until patches are available:
For SCALANCE W1750D: Users who do not use the OpenDNS, Captive Portal, or URL
redirection functionalities can deploy firewall rules in the device
configuration to block incoming access to Port 53/UDP.
For SCALANCE M800/S615: Disable DNS proxy in the device configuration (System
- - DNS - DNS Proxy - Disable Checkbox for Enable DNS Proxy) and configure the
connected devices in the internal network to use a different DNS server.
Siemens has produced an advisory that can be found at:
(link is external)
Siemens also reports that SCALANCE W1750D devices that are operated in
controller mode on an Aruba Mobility Controller are not affected if AOS
versions newer than V18.104.22.168, V22.214.171.124 V126.96.36.199, V188.8.131.52, V184.108.40.206, or
220.127.116.11 are used.
NCCIC/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 ICSCERT 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.
UNCONTROLLED RESOURCE CONSUMPTION ('RESOURCE EXHAUSTION') CWE-400
An attacker can cause a crash of the DNSmasq process by sending
specially-crafted request messages to the service.
The following CVEs have been assigned to this group of vulnerabilities:
A CVSS v3 base score of 5.3 has been assigned; the CVSS vector string is
IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER
An attacker can cause a crash or potentially execute arbitrary code by sending
specially-crafted DNS responses to the DNSmasq process. In order to exploit
this vulnerability, an attacker must be able to trigger DNS requests from the
device, and must be in a position that allows the injection of malicious DNS
CVE-2017-14491 has been assigned to this vulnerability. A CVSS v3 base score
of 8.1 has been assigned; the CVSS vector string is
Siemens Product CERT reported the vulnerabilities to ICS-CERT.
Critical Infrastructure Sectors: Chemical, Energy, Food and Agriculture,
Healthcare and Public Health, Transportation Systems, and Water and Wastewater
Countries/Areas Deployed: Worldwide
Company Headquarters Location: Germany
For any questions related to this report, please contact ICS-CERT at:
Email: firstname.lastname@example.org (link sends e-mail)
Toll Free: 1-877-776-7585
International Callers: (208) 526-0900
For industrial control systems security information and incident reporting:
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