ESB-2019.0443 - [Appliance] Siemens EN100 Ethernet Communication Module and SIPROTEC 5 Relays: Denial of service - Remote/unauthenticated 2019-02-13

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0443
             Advisory (ICSA-19-043-02) Siemens EN100 Ethernet
                Communication Module and SIPROTEC 5 Relays
                             13 February 2019

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

Product:           Siemens EN100 Ethernet Communication Module and SIPROTEC 5 Relays
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-16563  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-19-043-02

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Advisory (ICSA-19-043-02)

Siemens EN100 Ethernet Communication Module and SIPROTEC 5 Relays

Original release date: February 12, 2019

Legal Notice

All information products included in http://ics-cert.us-cert.gov are
provided"as is" for informational purposes only. The Department of Homeland
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For more information about TLP, see http://www.us-cert.gov/tlp/ .

1. EXECUTIVE SUMMARY

  o CVSS v3 7.5
  o ATTENTION: Exploitable remotely/low skill level to exploit
  o Vendor: Siemens
  o Equipment: EN100 Ethernet Communication Module and SIPROTEC 5 Relays
  o Vulnerability: Improper Input Validation

2. RISK EVALUATION

The EN100 Ethernet communication module and SIPROTEC 5 relays are affected by a
security vulnerability that could allow an attacker to conduct a
denial-of-service attack over the network.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports the vulnerability affects the following versions of the EN100
Ethernet Communication Module and SIPROTEC 5 relays:

  o Firmware variant IEC 61850 for EN100 Ethernet module: All versions prior to
    v4.35
  o Firmware variant MODBUS TCP for EN100 Ethernet module: All versions
  o Firmware variant DNP3 TCP for EN100 Ethernet module: All versions
  o Firmware variant IEC104 for EN100 Ethernet module: All versions
  o Firmware variant Profinet IO for EN100 Ethernet module: All versions
  o SIPROTEC 5 relays with CPU variants CP300 and CP100 and the respective
    Ethernet communication modules: All versions prior to v7.82
  o SIPROTEC 5 relays with CPU variants CP200 and the respective Ethernet
    communication modules: All versions prior to v7.58

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. Successful exploitation
requires an attacker with network access to send multiple packets to the
affected products or modules. As a precondition, the IEC 61850-MMS
communication needs to be activated on the affected products or modules. No
user interaction or privileges are required to exploit the vulnerability. The
vulnerability could allow a denial-of-service condition of the network
functionality of the device, compromising the availability of the system.

CVE-2018-16563 has been assigned to this vulnerability. A CVSS v3 base score of
7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/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

Lars Lengersdorf from Amprion GmbH reported this vulnerability to Siemens.

4. MITIGATIONS

Siemens has released updates for some affected products. Siemens is working on
updates for the remaining affected products, and recommends specific
countermeasures until fixes are available.

  o Firmware variant IEC 61850 for EN100 Ethernet module: Update to v4.35
    https://support.industry.siemens.com/cs/us/en/view/109745821
  o SIPROTEC 5 relays with CPU variants CP300 and CP100 and the respective
    Ethernet communication modules: Update to firmware version v7.82 for the
    device types listed in SSA-104088
  o SIPROTEC 5 relays with CPU variants CP200 and the respective Ethernet
    communication modules: Update to firmware version v7.58 for the device
    types listed in SSA-104088

The firmware version for the communications modules can also be found on each
device's download page. Applying the update causes the device module to undergo
a single restart cycle.

Until updates can be applied, Siemens recommends blocking access to Port 102/
TCP with an external firewall.

Siemens strongly recommends applying the provided security updates using the
corresponding tooling and documented procedures made available with the
product. If supported by the product, an automated means to apply the security
updates across multiple product instances may be used. Siemens strongly
recommends prior validation of any security update before application, and
supervision by trained staff of the update process in the target environment.

As a general security measure Siemens strongly recommends protecting network
access with appropriate mechanisms (e.g., firewalls, segmentation, VPN). Users
are advisded to configure the environment according to Siemens' operational
guidelines in order to run the devices in a protected IT environment.

Siemens recommended security guidelines to secure substations can be found at:
https://www.siemens.com/gridsecurity

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-104088 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.

No known public exploits specifically target this vulnerability.

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