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# SSA-573753: Remote Code Execution in Siemens LOGO! Web Server

Publication Date:        2020-07-14
Last Update:             2020-07-14
Current Version:         1.0
CVSS v3.1 Base Score:    9.8

SUMMARY
=======

The latest update for LOGO! 8 BM devices fixes a vulnerability that
could allow remote code execution in the web server functionality.

Siemens provides a firmware update for the latest versions of LOGO! BM.


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


* LOGO! 8 BM (incl. SIPLUS variants) 
  - Affected versions:
       V1.81.01 - V1.81.03
  - Remediation:
       Update to V1.81.04
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109780764/

* LOGO! 8 BM (incl. SIPLUS variants) 
  - Affected versions:
       V1.82.01
  - Remediation:
       Update to V1.82.03
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109780764/

* LOGO! 8 BM (incl. SIPLUS variants) 
  - Affected versions:
       V1.82.02
  - Remediation:
       Update to V1.82.04
  - Download:
       https://support.industry.siemens.com/cs/ww/en/view/109780764/


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

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

* Apply Defense-in-Depth concept, including protection concept outlined in
the system manual.
  


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

Siemens LOGO! BM (Base Module) devices are used for basic small-scale
automation tasks.

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-2020-7593

  A buffer overflow vulnerability exists in the Web Server functionality
  of the device. A remote unauthenticated attacker could send a specially
  crafted HTTP request to cause a memory corruption, potentially resulting
  in remote code execution.

  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-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')


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

Siemens thanks the following parties for their efforts:

   * Alexander Perez-Palma and Dave McDaniel from Cisco Talos for coordinated disclosure
   * Emanuel Almeida from Cisco Systems, Inc 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 (2020-07-14): 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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