ESB-2018.3063 - [Appliance] Siemen Simatic S7-1200: Cross-site request forgery - Remote with user interaction 2018-10-10

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.3063
   Advisory (ICSA-18-282-04 Siemens SIMATIC S7-1200 CPU Family Version 4
                              10 October 2018

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

Product:           Siemen Simatic S7-1200
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Cross-site Request Forgery -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-13800  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-18-282-04

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Advisory (ICSA-18-282-04)

Siemens SIMATIC S7-1200 CPU Family Version 4

Original release date: October 09, 2018

Legal Notice

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1. EXECUTIVE SUMMARY

  o CVSS v3 7.5
  o ATTENTION: Exploitable remotely
  o Vendor: Siemens
  o Equipment: SIMATIC S7-1200 CPU Family Version 4
  o Vulnerability: Cross-Site Request Forgery (CSRF)

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow a CSRF attack if an
unsuspecting user is tricked into accessing a malicious link.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Siemens reports the vulnerability affects the following SIMATIC S7-1200 CPU
products:

  o SIMATIC S7-1200 CPU Family Version 4: All versions prior to 4.2.3

3.2 VULNERABILITY OVERVIEW

3.2.1    CROSS-SITE REQUEST FORGERY (CSRF) CWE-352

The web interface could allow a CSRF attack if an unsuspecting user is tricked
into accessing a malicious link. Successful exploitation requires interaction
with a legitimate user, who must be authenticated to the web interface. A
successful attack could allow an attacker to trigger actions via the web
interface that the legitimate user is allowed to perform. This could allow the
attacker to read or modify parts of the device configuration.

CVE-2018-13800 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:H/PR:N/UI:R/S:U
/C:H/I:H/A:H).

3.3 BACKGROUND

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

3.4 RESEARCHER

Lisa Fournet and Marl Joos from P3 communications GmbH reported this
vulnerability to Siemens.

4. MITIGATIONS

Siemens provides a firmware update (v4.2.3) and recommends users 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/109741461

To reduce the risk, Siemens recommends users not visit other websites while
being authenticated against the PLC.

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-507847 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.

NCCIC also recommends that users take the following measures to protect
themselves from social engineering attacks:

  o Do not click web links or open unsolicited attachments in email messages.
  o Refer to Recognizing and Avoiding Email Scams for more information on
    avoiding email scams.
  o Refer to Avoiding Social Engineering and Phishing Attacks for more
    information on social engineering attacks.

High skill level is needed to exploit.

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