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AUSCERT External Security Bulletin Redistribution
Advisory (ICSA-17-243-02) Siemens LOGO!
1 September 2017
AusCERT Security Bulletin Summary
Product: Siemens LOGO!
Operating System: Network Appliance
Impact/Access: Access Privileged Data -- Remote with User Interaction
Provide Misleading Information -- Remote with User Interaction
CVE Names: CVE-2017-12735 CVE-2017-12734
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Original release date: August 31, 2017
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CVSS v3 7.5
ATTENTION: Remotely exploitable/low skill level to exploit.
Vulnerabilities: Insufficiently Protected Credentials, Man-in-the-Middle
Siemens reports that the vulnerabilities affect the following LOGO! devices:
LOGO!8 BM: All versions.
Successful exploitation of these vulnerabilities could allow an attacker to
hijack existing web sessions.
Siemens provides LOGO!8 BM FS-05 with firmware Version V1.81.2, which fixes
the first vulnerability.
Siemens recommends applying the following mitigations for users with existing
installations, and for mitigation of the second vulnerability:
Configure the environment according to the recommendations in the user manual:
https://support.industry.siemens.com/cs/us/en/view/109741041 (link is
Apply cell protection concept
Use VPN for protecting network communication between cells
(link is external)
As a general security measure, Siemens strongly recommends protecting network
access to the devices with appropriate mechanisms. Siemens advises configuring
the environment according to Siemens operational guidelines in order to run
the devices in a protected IT environment.
For more information on these vulnerabilities and more detailed mitigation
instructions, please see Siemens Security Advisory SSA-087240 at the following
http://www.siemens.com/cert/en/cert-security-advisories.htm (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 ICSCERT 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.
No known public exploits specifically target these vulnerabilities.
INSUFFICIENTLY PROTECTED CREDENTIALS CWE-522
An attacker with network access to the integrated web server on Port 80/TCP
could obtain the session ID of an active user session. A user must be logged
in to the web interface. Siemens recommends that users use the integrated
webserver on Port 80/TCP only in trusted networks.
CVE-2017-12734 has been assigned to this vulnerability. A CVSS v3 base score
of 7.5 has been calculated; the CVSS vector string is
CHANNEL ACCESSIBLE BY NON-ENDPOINT ('MAN-IN-THE-MIDDLE') CWE-300
An attacker who performs a Man-in-the-Middle attack between the LOGO! and
other devices could potentially decrypt and modify network traffic.
CVE-2017-12735 has been assigned to this vulnerability. A CVSS v3 base score
of 7.4 has been calculated; the CVSS vector string is
Maxim Rupp discovered one of these two vulnerabilities.
Critical Infrastructure Sectors: Commercial Facilities, Transportation Systems
Countries/Areas Deployed: Worldwide
Company Headquarters Location: Germany
For any questions related to this report, please contact ICS-CERT at:
Email: email@example.com (link sends e-mail)
Toll Free: 1-877-776-7585
International Callers: (208) 526-0900
For industrial control systems security information and incident reporting:
ICS-CERT continuously strives to improve its products and services. You can
help by choosing one of the links below to provide feedback about this
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