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# SSA-700697: Denial-of-Service Vulnerability in Web Server of SIMATIC Controllers

Publication Date:        2020-12-08
Last Update:             2020-12-08
Current Version:         1.0
CVSS v3.1 Base Score:    5.3

SUMMARY
=======

SIMATIC ET 200SP Open Controller V20.8 and SIMATIC S7-1500 Software
Controller V20.8 are affected by a denial-of-service vulnerability in
the web server.

Siemens has released updates for the affected products and recommends to
update to the latest version.


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


* SIMATIC ET 200SP Open Controller (incl. SIPLUS variants) 
  - Affected versions:
       V20.8
  - Remediation:
       Update to V21.8
  - Download:
       https://support.industry.siemens.com/cs/us/en/view/109759122

* SIMATIC S7-1500 Software Controller 
  - Affected versions:
       V20.8
  - Remediation:
       Update to V21.8
  - Download:
       https://support.industry.siemens.com/cs/us/en/view/109478528


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

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

* If the PC Station web server does not restart automatically Windows
reboot is required. This can be done while the control system is running
as the PLC control functionality is not affected.
  


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 SIMATIC ET 200SP Open Controller is a PC-based version of the
SIMATIC S7-1500 Controller including optional visualization in
combination with central I/Os in a compact device.

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.

SIMATIC S7-1500 Software Controller is a SIMATIC software controller for
PC-based automation solutions.

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-2020-15796

  The web server of the affected products contains a vulnerability that
  could allow a remote attacker to trigger a denial-of-service condition
  by sending a specially crafted HTTP request.

  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-248: Uncaught Exception




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 (2020-12-08): 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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