ESB-2019.0395 - [Appliance] Siemens EN100 Ethernet Module: Denial of service - Remote/unauthenticated 2019-02-08

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0395
                         Advisory (ICSA-19-038-02)
                              8 February 2019

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

Product:           Siemens EN100 Ethernet Module
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-11452 CVE-2018-11451 

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-19-038-02

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Advisory (ICSA-19-038-02)

Siemens EN100 Ethernet Module

Original release date: February 07, 2019

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1. EXECUTIVE SUMMARY

  o CVSS v3 7.5
  o ATTENTION : Exploitable remotely/low skill level to exploit
  o Vendor : Siemens
  o Equipment : EN100 Ethernet module
  o Vulnerabilities : Improper Input Validation

2. RISK EVALUATION

The EN100 Ethernet module for the SWT 3000 management platform is affected by
security vulnerabilities that could allow an attacker to conduct a
denial-of-service attack over the network.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of EN100 Ethernet module, a communication module for SWT
3000 management platform, are affected:

  o Firmware variant IEC 61850 for EN100 Ethernet module version prior to 4.33

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER INPUT VALIDATION CWE-20

Specially crafted packets to Port 102/TCP could cause a denial-of-service
condition in the affected products. A manual restart is required to recover the
EN100 module functionality of the affected devices.

CVE-2018-11451 has been assigned to this vulnerability. A CVSS v3 base score of
7.5 has been assigned; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/C:N/
I:N/A:H ).

3.2.2 IMPROPER INPUT VALIDATION CWE- 20

Specially crafted packets to Port 102/TCP could cause a denial-of-service
condition in the EN100 module if oscillographs are running. A manual restart is
required to recover the EN100 module functionality.

CVE-2018-11452 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:N/
I:N/A:H ).

3.3 BACKGROUND

  o CRITICAL INFRASTRUCTURE SECTORS : Energy
  o COUNTRIES/AREAS DEPLOYED : Worldwide
  o COMPANY HEADQUARTERS LOCATION : Germany

3.4 RESEARCHER

Victor Nikitin, Vladislav Suchkov, and Ilya Karpov from ScadaX reported these
vulnerabilities to Siemens.

4. MITIGATIONS

Siemens has released update v4.33 for several affected products, is working on
updates for the remaining affected products, and recommends specific
countermeasures until fixes are available:

https://support.industry.siemens.com/cs/us/en/view/109745821

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

  o Block access to Port 102/TCP.

For additional information see Siemens' security advisory SSA-325546 at the
following location:

http://www.siemens.com/cert/en/cert-security-advisories.htm

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.

No known public exploits specifically target these vulnerabilities.

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