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# SSA-296266: Denial-of-Service Vulnerability in SCALANCE and RUGGEDCOM Devices

Publication Date:        2021-03-09
Last Update:             2021-04-13
Current Version:         1.1
CVSS v3.1 Base Score:    8.6

SUMMARY
=======

Some firmware versions of the SCALANCE and RUGGEDCOM devices listed
below are affected by a vulnerability in the SSH authentication that
could allow an attacker to cause a Denial-of-Service under certain
conditions.

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


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


* RUGGEDCOM RM1224 
  - Affected versions:
       V6.3
  - Remediation:
       Update to V6.4 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109794349/

* SCALANCE M-800 
  - Affected versions:
       V6.3
  - Remediation:
       Update to V6.4 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109794349/

* SCALANCE S615 
  - Affected versions:
       V6.3
  - Remediation:
       Update to V6.4 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109794349/

* SCALANCE SC-600 
  - Affected versions:
       All Versions >= V2.1 and < V2.1.3
  - Remediation:
       Update to V2.1.3 or later version
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109793041/


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

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

* Configure the built-in firewall to only allow SSH incoming connections
from trusted 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
===================

The SCALANCE SC-600 devices (SC622-2C, SC632-2C, SC636-2C, SC642-2C,
SC646-2C) are used to protect trusted industrial networks from untrusted
networks. They allow filtering incoming and outgoing network connections
in different ways.

The SCALANCE M-800 / S615 industrial routers are used for secure remote
access to plants via mobile networks, e.g. GPRS or UMTS with the
integrated security functions of a firewall for protection against
unauthorized access and VPN to protect data transmission.

RUGGEDCOM RM1224 is a 4G ROUTER for wireless IP-communication from
Ethernet based devices via LTE(4G)- mobile radio.

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-2021-25676

  Multiple failed SSH authentication attempts could trigger a temporary
  Denial-of-Service under certain conditions. When triggered, the device
  will reboot automatically.

  CVSS v3.1 Base Score: 8.6
  CVSS Vector:          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C
  CWE:                  CWE-307: Improper Restriction of Excessive Authentication Attempts




ADDITIONAL INFORMATION
======================
This vulnerability has been discovered internally by Siemens.

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 (2021-03-09): Publication Date
V1.1 (2021-04-13): Added solution for SCALANCE M-800/S615 and RUGGEDCOM RM1224

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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