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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!
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Access Privileged Data         -- Remote with User Interaction
                   Provide Misleading Information -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-12735 CVE-2017-12734 

Original Bulletin: 

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Advisory (ICSA-17-243-02)

Siemens LOGO!

Original release date: August 31, 2017

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CVSS v3 7.5

ATTENTION: Remotely exploitable/low skill level to exploit.

Vendor: Siemens

Equipment: LOGO!

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

Apply Defense-in-Depth:

(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.

https://www.siemens.com/cert/operational-guidelines-industrial-security (link
is external)

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.



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 


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

Contact Information

For any questions related to this report, please contact ICS-CERT at:

Email: ics-cert@hq.dhs.gov (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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