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AUSCERT External Security Bulletin Redistribution
Advisory (ICSA-18-088-01) WAGO 750 Series
4 April 2018
AusCERT Security Bulletin Summary
Product: WAGO 750 Series
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2018-8836
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Advisory (ICSA-18-088-01) WAGO 750 Series
Original release date: March 29, 2018
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CVSS v3 5.3
ATTENTION: Exploitable remotely/low skill level to exploit.
Equipment: 750 Series
Vulnerability: Improper Resource Shutdown or Release
The following versions of 750 series PLC are affected:
750-880 firmware version 10 and prior,
750-881 firmware version 10 and prior,
750-852 firmware version 10 and prior,
750-882 firmware version 10 and prior,
750-885 firmware version 10 and prior,
750-831 firmware version 10 and prior,
750-889 firmware version 10 and prior, and
750-829 firmware version 10 and prior.
Successful exploitation of this vulnerability could allow a denial-of-service
condition affecting the ability of the device to establish connections to
commissioning and service software tools.
WAGO has released new firmware addressing this vulnerability that can be
obtained by contacting WAGO support via email at firstname.lastname@example.org (link sends
If updating the firmware is not feasible WAGO recommends that users disable
the WAGO Service Communication via WBM or limit the access to Ports 6626 and
2455/TCP/IP to trusted devices.
For more information see WAGOs security advisory:
Vulnerability-in-the-WAGO-Ethernet-TCP-IP-driver.pdf (link is external)
NCCIC recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. 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.
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 in the NCCIC 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 NCCIC for
tracking and correlation against other incidents.
No known public exploits specifically target this vulnerability.
IMPROPER RESOURCE SHUTDOWN OR RELEASE CWE-404
A remote attack may take advantage of an improper implementation of the 3 way
handshake during a TCP connection affecting the communications with commission
and service tools. Specially crafted packets may also be sent to Port
2455/TCP/IP, used in Codesys management software, which may result in a
denial-of-service condition of communications with commissioning and service
CVE-2018-8836 has been assigned to this vulnerability. A CVSS v3 base score of
5.3 has been assigned; the CVSS vector string is
Younes Dragoni of Nozomi Networks reported the vulnerability to NCCIC.
Critical Infrastructure Sectors: Commercial Facilities, Critical
Manufacturing, Energy, and Transportation Systems
Countries/Areas Deployed: Worldwide
Company Headquarters Location: United States, Germany, Switzerland, Poland,
China, and India
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