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# SSA-111512: Client-side Authentication in SIMATIC WinCC OA

Publication Date:        2022-06-21
Last Update:             2022-06-21
Current Version:         1.0
CVSS v3.1 Base Score:    9.8

SUMMARY
=======

SIMATIC WinCC OA implements client-side only authentication, when
neither server-side authentication (SSA) nor Kerberos authentication is
enabled. In this configuration, attackers could impersonate other users
or exploit the client-server protocol without being authenticated.

Siemens recommends to enable server-side authentication (SSA) or
Kerberos authentication for all WinCC OA projects, as documented in the
WinCC OA Security Guideline. In SIMATIC WinCC OA server-side
authentication is available since V3.15 (and offered as the default
configuration since V3.17). Additional information can be found at:
https://cert-portal.siemens.com/productcert/news.html?id=21.


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


* SIMATIC WinCC OA V3.16
  - Affected versions:
       All versions in default configuration
  - Remediation:
       Enable server-side authentication (SSA) or Kerberos authentication for
       your WinCC OA project
  - Download:
       https://www.winccoa.com/downloads/detail/security-guideline-wincc-oa-v316-1.html

* SIMATIC WinCC OA V3.17
  - Affected versions:
       All versions in non-default configuration
  - Remediation:
       Ensure that server-side authentication (SSA) is enabled for your WinCC
       OA project (which is the default configuration); alternatively enable
       Kerberos authentication
  - Download:
       https://www.winccoa.com/downloads/detail/security-guideline-wincc-oa-v317.html

* SIMATIC WinCC OA V3.18
  - Affected versions:
       All versions in non-default configuration
  - Remediation:
       Ensure that server-side authentication (SSA) is enabled for your WinCC
       OA project (which is the default configuration); alternatively enable
       Kerberos authentication
  - Download:
       https://www.winccoa.com/downloads/detail/security-guideline-wincc-oa-v318.html


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


Product specific remediations or mitigations can be found in the section
"Affected Products and Solution".

Please follow the "General Security Recommendations".


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

SIMATIC WinCC Open Architecture (OA) is part of the SIMATIC HMI family.
It is designed for use in applications requiring a high degree of
customer-specific adaptability, large or complex applications and
projects that impose specific system requirements or functions.

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-2022-33139

  Affected applications use client-side only authentication, when neither
  server-side authentication (SSA) nor Kerberos authentication is enabled.
  
  In this configuration, attackers could impersonate other users or
  exploit the client-server protocol without being authenticated.

  CVSS v3.1 Base Score: 9.8
  CVSS Vector:          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
  CWE:                  CWE-603: Use of Client-Side Authentication


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

Siemens thanks the following parties for their efforts:

   * Daniel dos Santos and Jos Wetzels from Forescout Technologies for coordinated disclosure



ADDITIONAL INFORMATION
======================
In SIMATIC WinCC OA server-side authentication is available since V3.15
(and offered as the default configuration since V3.17). Find additional
information at:
https://cert-portal.siemens.com/productcert/news.html?id=21.

This issue is also addressed, among other findings across the OT
industry, in a recent article from Forescout Vedere Labs, dubbed as
"OT:ICEFALL": https://www.forescout.com/research-labs/ot-icefall/

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 (2022-06-21): 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.

Copyright: Siemens 2022
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