ESB-2018.0997 - [Win] Siemens SIMATIC : Denial of service - Remote/unauthenticated 2018-04-04

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.0997
  Advisory (ICSA-18-088-03) Siemens SIMATIC PCS 7, SIMATIC WinCC, SIMATIC
          WinCC Runtime Professional, and SIMATIC NET PC Software
                               4 April 2018

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

Product:           Siemens SIMATIC
Publisher:         ICS-CERT
Operating System:  Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-4832  

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-18-088-03

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Advisory (ICSA-18-088-03) Siemens SIMATIC PCS 7, SIMATIC WinCC, SIMATIC WinCC
Runtime Professional, and SIMATIC NET PC Software 

Original release date: March 29, 2018

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 Security 
(DHS) does not provide any warranties of any kind regarding any information 
contained within. DHS does not endorse any commercial product or service, 
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For 
more information about TLP, see http://www.us-cert.gov/tlp/.

CVSS v3 7.5

ATTENTION: Exploitable remotely/low skill level to exploit.

Vendor: Siemens

Equipment: SIMATIC PCS 7, SIMATIC WinCC, SIMATIC WinCC Runtime Professional, 
and SIMATIC NET PC Software

Vulnerability: Improper Input Validation

AFFECTED PRODUCTS

Siemens reports that the vulnerability affects the following SIMATIC products:

    OpenPCS 7 V7.1 and earlier,
    OpenPCS 7 V8.0: All versions,
    OpenPCS 7 V8.1: All versions,
    OpenPCS 7 V8.2: All versions,
    OpenPCS 7 V9.0: All versions prior to V9.0 Upd1,
    SIMATIC BATCH V7.1 and earlier,
    SIMATIC BATCH V8.0: All versions,
    SIMATIC BATCH V8.1: All versions,
    SIMATIC BATCH V8.2: All versions,
    SIMATIC BATCH V9.0: All versions prior to V9.0 SP1,
    SIMATIC NET PC-Software: All versions,
    SIMATIC PCS 7 V7.1 and earlier,
    SIMATIC PCS 7 V8.0: All versions,
    SIMATIC PCS 7 V8.1: All versions,
    SIMATIC PCS 7 V8.2: All versions,
    SIMATIC PCS 7 V9.0: All versions prior to V9.0 SP1,
    SIMATIC Route Control V7.1 and earlier,
    SIMATIC Route Control V8.0: All versions,
    SIMATIC Route Control V8.1: All versions,
    SIMATIC Route Control V8.2: All versions,
    SIMATIC Route Control V9.0: All versions prior to V9.0 Upd1,
    SIMATIC WinCC Runtime Professional: All versions prior to V14 SP1 Upd5,
    SIMATIC WinCC 7.2 and earlier,
    SIMATIC WinCC 7.3: All versions prior to WinCC 7.3 Upd16, and
    SIMATIC WinCC 7.4: All versions prior to V7.4 SP1 Upd4

IMPACT

Successful exploitation of this vulnerability could allow an attacker to cause
a denial-of-service condition on the remote and local communication 
functionality of the affected products. A system reboot is required to 
recover.

MITIGATION

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

    Upgrade to a newer PCS 7 version.

    Ensure that SIMATIC WinCC, SIMATIC WinCC Runtime Professional and SIMATIC
PCS 7 stations communicate via encrypted channels (i.e., activate feature 
Encrypted Communication in SIMATIC WinCC V7.3 or newer and SIMATIC PCS 7 V8.1
or newer). Enabling Encrypted Communication completely mitigates the 
vulnerability.

    Apply cell protection concept.
    Use VPN for protecting network communication between cells.
    Apply Defense-in-Depth.

Siemens has released updates for several affected products and recommends 
users update to the new version. Siemens is preparing further updates and 
recommends specific countermeasures until patches are available:

    SIMATIC PCS 7 V9.0: Install V9.0 SP1:

Contact local support.

    SIMATIC WinCC Runtime Professional: Update to V14 SP1 Upd5:

https://support.industry.siemens.com/cs/ww/en/view/109747394 (link is 
external)

    SIMATIC WinCC V7.3: Update to WinCC 7.3 Upd16:

https://support.industry.siemens.com/cs/ww/en/view/109756123 (link is 
external)

    SIMATIC WinCC V7.4: Update to V7.4 SP1 Upd4

https://support.industry.siemens.com/cs/ww/en/view/109753031 (link is 
external)

As a general security measure, Siemens strongly recommends protecting network
access to devices with appropriate mechanisms. In order to run the devices in
a protected IT environment, Siemens particularly recommends that users 
configure the environment according to Siemens Operational Guidelines for 
Industrial Security (link is external) and follow the recommendations in the 
product manuals.

Additional information on industrial security by Siemens can be found at:

https://www.siemens.com/industrialsecurity (link is external)

For more information on this vulnerability and associated software updates, 
please see Siemens security advisory SSA-348629 on their website:

https://www.siemens.com/cert/advisories (link is external)

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

    Minimize network exposure for all control system devices and/or systems, 
and ensure that they are not accessible from the Internet.

    Locate control system networks and remote devices behind firewalls, and 
isolate them from the business network.

    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 in the NCCIC Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies, that is available for download from the ICS-CERT website.

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.

VULNERABILITY OVERVIEW

IMPROPER INPUT VALIDATION CWE-20

Specially crafted messages sent to the RPC service of the affected products 
could cause a denial-of-service condition on the remote and local 
communication functionality of the affected products. A reboot of the system 
is required to recover the remote and local communication functionality.

CVE-2018-4832 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).

RESEARCHER

Vladimir Dashchenko from Kaspersky Lab and independent researcher cdev1 
reported this vulnerability to Siemens.

BACKGROUND

Critical Infrastructure Sectors: Chemical, Energy, Food and Agriculture, Water
and Wastewater Systems.

Countries/Areas Deployed: Worldwide

Company Headquarters Location: Germany

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