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# SSA-987029: Denial-of-Service Vulnerability in SIMATIC S7-300 CPU Family

Publication Date:        2015-03-05
Last Update:             2020-02-10
Current Version:         1.1
CVSS v3.1 Base Score:    7.5

SUMMARY
=======

A vulnerability could allow attackers to perform a Denial-of-Service
attack over the network without prior authentication against S7-300 CPUs
under certain conditions.

Siemens recommends specific mitigations. Siemens will update this
advisory when new information becomes available.


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


* SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants) 
  - Affected versions:
       All versions
  - Remediation:
        See recommendations from section Workaround and Mitigations


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

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

* Apply protection-level 3 (Read/Write protection)
  
* Apply cell protection concept (see
https://www.siemens.com/cert/operational-guidelines-industrial-security)
  
* Use VPN for protecting network communication between cells
  
* Apply Defense-in-Depth (see
http://www.industry.siemens.com/topics/global/en/industrial-security/concept/Pages/defense-in-depth.aspx)
  


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 Siemens SIMATIC S7-300 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-2015-2177

  Specially crafted packets sent to port 102/tcp (ISO-TSAP) or via
  Profibus could cause the affected device to go into defect mode. A cold
  restart is required to recover the system.

  CVSS v3.1 Base Score: 7.5
  CVSS Vector:          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:C
  CWE:                  CWE-730: OWASP Top Ten 2004 Category A9 - Denial of Service


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

Siemens thanks the following parties for their efforts:

   * Johannes Klick, Christian Pfahl, Martin Gebert, and Lucas Jacob from Freie Universität Berlin's work team SCADACS for coordinated disclosure
   * 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 (2015-03-05): Publication Date
V1.1 (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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