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AUSCERT External Security Bulletin Redistribution
ESB-2019.4313
Advisory (icsa-19-318-03) Siemens Desigo PX Devices
15 November 2019
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens Desigo PX
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2019-13927
Original Bulletin:
https://www.us-cert.gov/ics/advisories/icsa-19-318-03
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ICS Advisory (ICSA-19-318-03)
Siemens Desigo PX Devices
Original release date: November 14, 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
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/ .
1. EXECUTIVE SUMMARY
o CVSS v35.3
o ATTENTION : Exploitable remotely/low skill level to exploit
o Vendor : Siemens
o Equipment : Desigo PX Devices
o Vulnerability : External Control of Assumed-Immutable Web Parameter
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to cause
a denial-of-service condition on the device's web server, requiring a reboot to
recover the web interface.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following Desigo PX automation controllers are affected:
o PXC00-E.D, PXC50-E.D, PXC100-E.D, PXC200-E.D with Desigo PX Web modules
PXA40-W0, PXA40-W1, PXA40-W2: All firmware versions prior to V6.00.320
o PXC00-U, PXC64-U, PXC128-U with Desigo PX Web modules
PXA30-W0, PXA30-W1, PXA30-W2: All firmware versions prior to V6.00.320
o PXC22.1-E.D, PXC36-E.D, PXC36.1-E.D with activated web server: All firmware
versions prior to V6.00.320
3.2 VULNERABILITY OVERVIEW
3.2.1 EXTERNAL CONTROL OF ASSUMED-IMMUTABLE WEB PARAMETER CWE-472
An attacker with network access to an affected device could send a specially
crafted HTTP message to the web server port (TCP/80), which would cause the
server to reply with status code 404 to any further requests. Exploitation
requires no system privileges and no user interaction. A reboot is required to
recover the web interface. This vulnerability may impact the availability of
the affected system.
CVE-2019-13927 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/
C:N/I:N/A:L ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS : Chemical, Critical Manufacturing, Energy,
Food and Agriculture, Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED : Worldwide
o COMPANY HEADQUARTERS LOCATION : Germany
3.4 RESEARCHER
Gjoko "LiquidWorm" Krstic from Zero Science Lab (MK) reported this
vulnerability to Siemens.
4. MITIGATIONS
Siemens has an update available for the following affected products:
o PXC00-E.D, PXC50-E.D, PXC100-E.D, PXC200-E.D with Desigo PX Web modules
PXA40-W0, PXA40-W1, PXA40-W2: Install v6.00.320 or a later version .
o PXC00-U, PXC64-U, PXC128-U with Desigo PX Web modules
PXA30-W0, PXA30-W1, PXA30-W2: Install v6.00.320 or a later version .
o PXC22.1-E.D, PXC36-E.D, PXC36.1-E.D with activated web server: Install
v6.00.320 or a later version .
Siemens has identified the following specific workarounds and mitigations that
users can apply to reduce risk:
o Ensure the PX Web interface is accessible only from trusted networks.
As a general security measure, Siemens strongly recommends customers protect
network access to affected products with appropriate mechanisms. Siemens
advises all users to follow recommended security practices to run the devices
in a protected environment.
For more information on security vulnerabilities in Siemens products and
solutions, please contact the Siemens ProductCERT:
http://www.siemens.com/cert/advisories
For more information on the vulnerability and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-898181 at the following
location: http://www.siemens.com/cert/advisories
CISA 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.
CISA reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices
on the ICS webpage on us-cert.gov . 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 webpage on us-cert.gov 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 CISA for tracking
and correlation against other incidents.
No known public exploits specifically target this vulnerability.
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