ESB-2017.2190 - [Appliance] Siemens 7KM PAC Switched Ethernet: Denial of service - Remote/unauthenticated 2017-09-01

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2017.2190
        Advisory (ICSA-17-243-03) Siemens 7KM PAC Switched Ethernet
                             1 September 2017

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Siemens 7KM PAC Switched Ethernet
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-9945  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-17-243-03

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Advisory (ICSA-17-243-03)

Siemens 7KM PAC Switched Ethernet

Original release date: August 31, 2017

Legal Notice

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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/.

CVSS v3 4.3

ATTENTION: Low skill level to exploit.

Vendor: Siemens

Equipment: 7KM PAC Switched Ethernet

Vulnerability: Resource Exhaustion

AFFECTED PRODUCTS

Siemens reports that the vulnerability affects the following 7KM PAC Switched
Ethernet PROFINET expansion modules:

7KM PAC Switched Ethernet PROFINET expansion module: All versions prior to 
V2.1.3

IMPACT

Successful exploitation of this vulnerability could cause a denial-of-service
condition in the affected component that may require a manual restart of the 
main device to recover.

MITIGATION

Siemens provides firmware Version V2.1.3 [1] for 7KM PAC Switched Ethernet 
PROFINET expansion modules, which fixes the vulnerability, and recommends 
users to update to the new fixed version. The new firmware update can be found
at the following location:

https://support.industry.siemens.com/cs/ww/en/view/109749555 (link is 
external)

Siemens recommends users protect network access with appropriate mechanisms 
such as firewalls, segmentation, and VPNs. Siemens also advises that users 
configure the operational environment according to Siemens Operational 
Guidelines for Industrial Security:

https://www.siemens.com/cert/operational-guidelines-industrial-security (link
is external)

For more information on this vulnerability and more detailed mitigation 
instructions, please see Siemens Security Advisory SSA-771218 at the following
location:

http://www.siemens.com/cert/advisories (link is external)

NCCIC/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. 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.

No known public exploits specifically target this vulnerability. This 
vulnerability is not remotely exploitable.

VULNERABILITY OVERVIEW

UNCONTROLLED RESOURCE CONSUMPTION ('RESOURCE EXHAUSTION') CWE-400

A denial-of-service condition could be induced by a specially crafted PROFINET
DCP packet sent as a local Ethernet (Layer 2) broadcast. The affected 
component requires a manual restart via the main device to recover.

CVE-2017-9945 has been assigned to this vulnerability. A CVSS v3 base score of
4.3 has been calculated; the CVSS vector string is 
(AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

RESEARCHER

Siemens reported this vulnerability and released an advisory with firmware 
update information.

BACKGROUND

Critical Infrastructure Sectors: Energy

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Germany

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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