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# SSA-594364: Denial-of-Service Vulnerability in SNMP Implementation of WinCC Runtime

Publication Date:        2021-05-11
Last Update:             2021-05-11
Current Version:         1.0
CVSS v3.1 Base Score:    5.3

SUMMARY
=======

A denial-of-service vulnerability in WinCC Runtime could allow an
unauthenticated attacker with network access to cause a
denial-of-service condition in the SNMP service by sending crafted SNMP
packets to port 161/udp.

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


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


* SIMATIC HMI Comfort Panels 1st Generation (incl. SIPLUS variants) 
  - Affected versions:
       All versions < V16 Update 4
  - Remediation:
       Update to V16 Update 4 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109775861/

* SIMATIC HMI KTP Mobile Panels 
  - Affected versions:
       All versions < V16 Update 4
  - Remediation:
       Update to V16 Update 4 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109775861/


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

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

* Disable SNMP if this is supported by the product. Disabling SNMP fully
mitigates the vulnerability

* Restrict network access to port 161/udp of affected devices to trusted
devices or IP addresses



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 HMI Panels are used for operator control and monitoring of
machines and plants.

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-2019-19276

  Specially crafted packets sent to port 161/udp can cause the SNMP
  service of affected devices to crash. A manual restart of the device is
  required to resume operation of the service.

  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-787: Out-of-bounds Write


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

Siemens thanks the following parties for their efforts:

   * Younes Dragoni and Alessandro Di Pinto from Nozomi Networks for coordinated 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 (2021-05-11): 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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