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# SSA-589181: Denial-Of-Service in SIMATIC S7-200 SMART CPU Family Devices

Publication Date:        2020-07-14
Last Update:             2020-07-14
Current Version:         1.0
CVSS v3.1 Base Score:    7.5

SUMMARY
=======

The latest update for SIMATIC S7-200 SMART fixes a vulnerability that
could allow an attacker to cause a permanent Denial-of-Service of an
affected device by sending a large number of crafted packets.

Siemens has released an update for the SIMATIC S7-200 SMART CPU family
and recommends that customers update to the latest version.


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


* SIMATIC S7-200 SMART CPU family 
  - Affected versions:
       All versions >= V2.2 < V2.5.1
  - Remediation:
       Update to V2.5.1
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109765009/


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

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

* Limit network access to device to trusted sources.
  


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
===================

The S7-200 SMART series is a line of micro-programmable logic
controllers that can control a variety of small automation applications.

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-2020-7584

  Affected devices do not properly handle large numbers of new incomming
  connections and could crash under certain circumstances. An attacker may
  leverage this to cause a Denial-of-Service situation.

  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:O/RC:C
  CWE:                  CWE-400: Uncontrolled Resource Consumption


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

Siemens thanks the following parties for their efforts:

   * Ezequiel Fernandez from Dreamlab Technologies for related disclosure



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 (2020-07-14): Publication Date

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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