ESB-2018.3064 - [Appliance] Siemens Scalance W1750D: Access privileged data - Remote/unauthenticated 2018-10-10

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.3064
             Advisory (ICSA-18-282-02) Siemens SCALANCE W1750D
                              10 October 2018

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Siemens Scalance W1750D
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Access Privileged Data -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-13099  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-18-282-02

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Advisory (ICSA-18-282-02)

Siemens SCALANCE W1750D

Original release date: October 09, 2018

Legal Notice

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1. EXECUTIVE SUMMARY

  o CVSS v3 5.9
  o ATTENTION: Exploitable remotely/public exploits are available
  o Vendor: Siemens
  o Equipment: SCALANCE W1750D
  o Vulnerability: Cryptographic issues

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to
decrypt TLS traffic.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports the vulnerability affects the following SCALANCE W1750D
products: 

  o SCALANCE W1750D: All versions prior to v8.3.0.1

3.2 VULNERABILITY OVERVIEW

3.2.1    CRYPTOGRAPHIC ISSUES CWE-310

An attacker with network access to affected devices could potentially obtain a
TLS session key. If the attacker is able to observe TLS traffic between a
legitimate user and the device, the attacker could decrypt the TLS traffic.

CVE-2017-13099 has been assigned to this vulnerability. A CVSS v3 base score
of 5.9 has been assigned; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/
C:H/I:N/A:N).

3.3 BACKGROUND

  o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Energy, Food and Agriculture,
    Healthcare and Public Health, Transportation Systems, Water and Wastewater
    Systems
  o COUNTRIES/AREAS DEPLOYED: Worldwide
  o COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported this vulnerability to NCCIC.

4. MITIGATIONS

Siemens provides a firmware update (v8.3.0.1) and recommends users to update
to the new version. This update can be found on their website at the following
location:

https://support.industry.siemens.com/cs/us/en/view/109760581 

To reduce the risk, Siemens recommends administrators restrict access to the
web interface of the affected devices.

As a general security measure, Siemens strongly recommends protecting network
access to devices with appropriate mechanisms. In order to operate the devices
in a protected IT environment, Siemens recommends configuring the environment
according to Siemens' operational guidelines for industrial security (https://
www.siemens.com/cert/operational-guidelines-industrial-security), and
following the recommendations in the product manuals.

Additional information on Industrial Security by Siemens can be found at: 

https://www.siemens.com/industrialsecurity

For more information on this vulnerability and associated software updates,
please see Siemens security advisory SSA-464260 on their website:

https://www.siemens.com/cert/advisories

NCCIC recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:

  o Minimize network exposure for all control system devices and/or systems,
    and ensure that they are not accessible from the Internet.
  o Locate control system networks and remote devices behind firewalls, and
    isolate them from the business network.
  o When remote access is required, use secure methods, such as Virtual
    Private Networks (VPNs), recognizing that VPNs may have vulnerabilities
    and should be updated to the most current version available. Also
    recognize that VPN is only as secure as the connected devices.

NCCIC reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.

NCCIC also provides a section for control systems security recommended
practices on the ICS-CERT web page. Several recommended practices are
available for reading and download, including Improving Industrial Control
Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly
available on the ICS-CERT website in the Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies.

Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to NCCIC for
tracking and correlation against other incidents.

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