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AUSCERT External Security Bulletin Redistribution
ESB-2017.0945
Advisory (ICSA-17-101-01) Schneider Electric Modicon Modbus Protocol
12 April 2017
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AusCERT Security Bulletin Summary
---------------------------------
Product: Modicon Modbus Protocol
Publisher: Schneider Electric
Operating System: Network Appliance
Impact/Access: Provide Misleading Information -- Remote with User Interaction
Resolution: Mitigation
CVE Names: CVE-2017-6034 CVE-2017-6032
Original Bulletin:
http://ics-cert.us-cert.gov/advisories/ICSA-17-101-01
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Advisory (ICSA-17-101-01)
Schneider Electric Modicon Modbus Protocol
Original release date: April 11, 2017
Legal Notice
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more information about TLP, see http://www.us-cert.gov/tlp/.
CVSS v3 10.0
ATTENTION: Remotely exploitable/low skill level to exploit.
Vendor: Schneider Electric
Equipment: Modicon Modbus Protocol
Vulnerabilities: Authentication Bypass by Capture-Replay, Violation of Secure
Design Principles
AFFECTED PRODUCTS
The following versions of Modicon Modbus protocol, which can be used with the
Modicon family of programmable logic controllers (PLCs), are affected:
Modicon Modbus protocol, all versions.
IMPACT
Successful exploitation of these vulnerabilities may allow an unauthorized
remote attacker to capture and replay sensitive commands to PLCs on a network
using the Modicon Modbus protocol.
MITIGATION
Schneider Electric has reported that they have introduced compensating
controls to limit the exploitability of the identified vulnerabilities in many
of the PLCs in the Modicon family; however, Schneider Electric recommends that
users apply security measures to improve resiliency.
Schneider Electric's Momentum M1E controllers (all versions of model
171CBU98090 and all versions of model 171CBU98091) do not have built-in
compensating controls to limit the exploitability of the identified
vulnerabilities and Schneider Electric instructs users to take the following
defensive measures:
Protect access to M1E controllers by a firewall blocking all remote/external
access to Port 502.
Schneider Electric reports that Modicon M340, M580, Premium and Quantum users
should take one or more of the following defensive measures:
Enable protection based on an authentication to connect to PLC. This method
relies on a feature named Application Password. Once enabled, password-based
authentication is required whenever a user connects to change their
application program;
Enable protection relying on an input (M340, Premium, Quantum) or a key switch
in the front panel (Quantum) to reject remote connection or run/stop commands;
and
Enable the "Access Control List protection," where users are able to configure
the restricted IP addresses that are pre-authorized to control the PLC.
For additional information, Schneider Electric has released a Cybersecurity
Notification, which is available at the following location:
http://www.schneider-electric.com/en/download/document/SEVD-2017-065-01/ (link
is external)
NCCIC/ICS-CERT recommends that users take defensive measures to minimize the
risk of exploitation of these vulnerabilities. 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.
ICS-CERT reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
ICS-CERT 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 ICS-CERT Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies, that is available for download from the ICS-CERT web site.
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to ICS-CERT for
tracking and correlation against other incidents.
VULNERABILITY OVERVIEW
AUTHENTICATION BYPASS BY CAPTURE-REPLAY CWE-294
Sensitive information is transmitted in cleartext in the Modicon Modbus
protocol, which may allow an attacker to replay the following commands: run,
stop, upload, and download.
CVE-2017-6034 has been assigned to this vulnerability. A CVSS v3 base score of
10.0 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)
VIOLATION OF SECURE DESIGN PRINCIPLES CWE-657
The Modicon Modbus protocol has a session-related weakness making it
susceptible to brute-force attacks.
CVE-2017-6032 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been assigned; the CVSS vector string is
(AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).
RESEARCHER
Eran Goldstein of CRITIFENCE reported the identified vulnerabilities.
BACKGROUND
Critical Infrastructure Sectors: Critical Manufacturing, Dams, Defense
Industrial Base, Energy, Food and Agriculture, Government Facilities, Nuclear
Reactors, Materials, and Waste, Transportation Systems, and Water and
Wastewater Systems
Countries/Areas Deployed: Worldwide
Company Headquarters Location: Paris, France
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