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# SSA-584286: Denial-of-Service Vulnerability in SIMATIC S7-1200 CPU and SIMATIC
S7-1500 CPU

Publication Date:        2018-11-13
Last Update:             2020-02-10
Current Version:         1.2
CVSS v3.1 Base Score:    5.3

SUMMARY
=======

A vulnerability was identified in SIMATIC S7-1200 and S7-1500 CPUs that
could allow an attacker to cause a denial-of-service condition
preventing HMI or engineering access to the PLC over port 102/tcp.

Siemens has released an update for the S7-1500 product and recommends
that customers update to the new version. Siemens is preparing a further
update for the S7-1200 product and recommends specific workarounds and
mitigations until patches are available.


AFFECTED PRODUCTS AND SOLUTION
==============================


* SIMATIC S7-1200 CPU family (incl. SIPLUS variants) 
  - Affected versions:
       All Versions < V4.3
  - Remediation:
       Update to V4.3
  - Download:
       https://support.industry.siemens.com/cs/us/en/view/109763919

* SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS
variants) 
  - Affected versions:
       All Versions < V2.6
  - Remediation:
       Update to V2.6
  - Download:
       https://support.industry.siemens.com/cs/de/en/view/109478459


WORKAROUNDS AND MITIGATIONS
===========================

Siemens has identified the following specific workarounds and mitigations that
customers can apply to reduce the risk:

* Protect network access to port 102/tcp of affected devices
  
* Apply cell-protection concept
  
* Apply defense-in-depth
  


GENERAL SECURITY RECOMMENDATIONS
================================

As a general security measure, Siemens strongly recommends to protect
network access to devices with appropriate mechanisms. In order to
operate the devices in a protected IT environment, Siemens recommends to
configure the environment according to Siemens' operational guidelines
for Industrial Security (Download:
https://www.siemens.com/cert/operational-guidelines-industrial-security),
and to follow the recommendations in the product manuals.

Additional information on Industrial Security by Siemens can be found
at: https://www.siemens.com/industrialsecurity

PRODUCT DESCRIPTION
===================

Products of the SIMATIC S7-1200 CPU family have been designed for
discrete and continuous control in industrial environments such as
manufacturing, food and beverages, and chemical industries worldwide.

Products of the SIMATIC S7-1500 CPU family have been designed for
discrete and continuous control in industrial environments such as
manufacturing, food and beverages, and chemical industries worldwide.

SIPLUS extreme products are designed for reliable operation under
extreme conditions and are based on SIMATIC, LOGO!, SITOP, SINAMICS,
SIMOTION, SCALANCE or other devices. SIPLUS devices use the same
firmware as the product they are based on.

VULNERABILITY CLASSIFICATION
============================

The vulnerability classification has been performed by using the CVSS scoring
system in version 3.1 (CVSS v3.1) (https://www.first.org/cvss/). The CVSS 
environmental score is specific to the customer's environment and will impact
the overall CVSS score. The environmental score should therefore be 
individually defined by the customer to accomplish final scoring.

An additional classification has been performed using the CWE classification, a
community-developed list of common software security weaknesses. This serves as
a common language and as a baseline for weakness identification, mitigation,
and prevention efforts. A detailed list of CWE classes can be found at:
https://cwe.mitre.org/.



* Vulnerability CVE-2018-13815

  An attacker could exhaust the available connection pool of an affected
  device by opening a sufficient number of connections to the device.
  
  Successful exploitation requires an attacker to be able to send packets
  to port 102/tcp of the affected device. No user interaction and no user
  privileges are required to exploit the vulnerability. The vulnerability,
  if exploited, could cause a Denial-of-Service condition impacting the
  availability of the system.
  
  At the time of advisory publication no public exploitation of this
  vulnerability was known.

  CVSS v3.1 Base Score: 5.3
  CVSS Vector:          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
  CWE:                  CWE-410: Insufficient Resource Pool


ACKNOWLEDGMENTS
===============

Siemens thanks the following parties for their efforts:

   * Younes Dragoni from Nozomi Networks for coordinated disclosure
   * Industrial Control System Cyber Emergency Response Team (ICS-CERT) for coordination efforts
   * Artem Zinenko from Kaspersky for pointing out that SIPLUS should also be mentioned



ADDITIONAL INFORMATION
======================

For further inquiries on security vulnerabilities in Siemens products and 
solutions, please contact the Siemens ProductCERT:

https://www.siemens.com/cert/advisories


HISTORY DATA
============

V1.0 (2018-11-13): Publication Date
V1.1 (2019-03-12): Added solution for SIMATIC S7-1200
V1.2 (2020-02-10): SIPLUS devices now explicitly mentioned in the list of affected products

TERMS OF USE
============

Siemens Security Advisories are subject to the terms and conditions contained
in Siemens' underlying license terms or other applicable agreements previously
agreed to with Siemens (hereinafter "License Terms"). To the extent applicable
to information, software or documentation made available in or through a
Siemens Security Advisory, the Terms of Use of Siemens' Global Website
(https://www.siemens.com/terms_of_use, hereinafter "Terms of Use"), in
particular Sections 8-10 of the Terms of Use, shall apply additionally. In case
of conflicts, the License Terms shall prevail over the Terms of Use.
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