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# SSA-686152: Denial-of-Service Vulnerability in ARP Protocol of SCALANCE W780 and
W740

Publication Date:        2021-02-09
Last Update:             2021-02-09
Current Version:         1.0
CVSS v3.1 Base Score:    4.3

SUMMARY
=======

A Denial-of-Service vulnerability was found affecting the ARP protocol
on older firmware versions of the SCALANCE W780 and W740 (IEEE 802.11n)
devices.

Siemens recommends to update to the latest version.


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


* SCALANCE W780 and W740 (IEEE 802.11n) family 
  - Affected versions:
       All versions < V6.3
  - Remediation:
       Update to V6.3 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109781235/


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


Siemens has not identified any specific mitigations or workarounds.
Please follow 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
===================

SCALANCE W700 products are wireless communication devices used to
connect industrial components like Programmable Logic Controllers (PLCs)
or Human Machine Interfaces (HMIs).

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-2021-25666

  Sending specially crafted packets through the ARP protocol to an
  affected device could cause a partial denial-of-service, preventing the
  device to operate normally for a short period of time.

  CVSS v3.1 Base Score: 4.3
  CVSS Vector:          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
  CWE:                  CWE-770: Allocation of Resources Without Limits or Throttling




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 (2021-02-09): 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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