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# SSA-830194: Missing Authentication Vulnerability in S7-1200 Devices

Publication Date:        2021-08-10
Last Update:             2021-09-14
Current Version:         1.1
CVSS v3.1 Base Score:    8.1

SUMMARY
=======

SIMATIC S7-1200 PLC, version V4.5.0 fails to authenticate against
configured passwords when the affected device was provisioned using TIA
Portal V13. This could allow an attacker using TIA Portal V13 or later
versions to bypass authentication and download arbitrary programs to the
PLC.

Siemens has released an update for SIMATIC S7-1200 and recommends to
update to the latest version.


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


* SIMATIC S7-1200 CPU family (incl. SIPLUS variants) 
  - Affected versions:
       V4.5.0
  - Remediation:
       Update to V4.5.1 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109793280/


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

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

* Update to TIA Portal V13 SP1 or any later version before provisioning
S7-1200 V4.5.0 devices



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.

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-2021-37172

  Affected devices fail to authenticate against configured passwords when
  provisioned using TIA Portal V13. This could allow an attacker using TIA
  Portal V13 or later versions to bypass authentication and download
  arbitrary programs to the PLC. The vulnerability does not occur when TIA
  Portal V13 SP1 or any later version was used to provision the device.

  CVSS v3.1 Base Score: 8.1
  CVSS Vector:          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
  CWE:                  CWE-287: Improper Authentication


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

Siemens thanks the following parties for their efforts:

   * Gao Jian for reporting the vulnerability



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 (2021-08-10): Publication Date
V1.1 (2021-09-14): Clarified that the use of TIA Portal V13 or later (not only V17 or
later) could allow a successful attack

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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