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AUSCERT External Security Bulletin Redistribution
Advisory (ICSA-19-136-01) Schneider Electric Modicon Controllers
17 May 2019
AusCERT Security Bulletin Summary
Product: Schneider Electric Modicon Controllers
Operating System: Network Appliance
Impact/Access: Unauthorised Access -- Remote/Unauthenticated
CVE Names: CVE-2018-7838
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Schneider Electric Modicon Controllers
Original release date: May 16, 2019
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1. EXECUTIVE SUMMARY
o CVSS v3 5.4
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Schneider Electric
o Equipment: Modicon M580, Modicon M340, Modicon Premium, and Modicon Quantum
o Vulnerability: Use of Insufficiently Random Values
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to hijack
TCP connections or cause information leakage.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Modicon products are affected:
o Modicon M580 firmware versions prior to Version 2.30
o Modicon M340 firmware, all versions
o Modicon Premium, all firmware versions
o Modicon Quantum, all firmware versions
3.2 VULNERABILITY OVERVIEW
3.2.1 USE OF INSUFFICIENTLY RANDOM VALUES CWE-330
The device has predictable TCP initial sequence numbers that allow attackers to
hijack TCP connections carrying unsecured communications.
CVE-2018-7838 has been assigned to this vulnerability. A CVSS v3 base score of
5.4 has been calculated; the CVSS vector string is ( AV:A/AC:L/PR:N/UI:N/S:U/
o CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: France
David Formby and Raheem Beyah of Fortiphyd Logic and Georgia Tech reported this
vulnerability to NCCIC.
Schneider Electric reports the following mitigations:
o Modicon M580 firmware Version 2.80 is available for download. For more
information see Schneider Electric advisory SEVD-2019-134-03
o Modicon M340: currently, no fix is available.
Schneider Electric recommends that affected users set up network
segmentation and implement a firewall to block all remote/external
access to TCP ports.
Configure the Access Control List following the recommendations of the
user manual "Modicon M340 for Ethernet Communications Modules and
Processors User Manual," in the chapter titled "Messaging Configuration
Parameters," which is available here: https://
o Modicon Premium and Modicon Quantum
Set up network segmentation and implement a firewall to block all
unauthorized access to all TCP ports.
In December 2018, Schneider Electric reported that the Modicon Premium and
Quantum controllers reached the End of Commercialization life cycle. For more
information, please see Schneider Electric advisory SEVD-2019-134-03
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
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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