Schneider Mitigations for Modicon M221 Hole

Tuesday, November 20, 2018 @ 06:11 PM gHale

Schneider Electric set up mitigations to handle an insufficient verification of data authenticity vulnerability in its Modicon M221, according to a report with NCCIC.

Successful exploitation of this vulnerability could cause a change of IPv4 configuration (IP address, mask, and gateway) when remotely connected to the device.

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Modicon M221, all versions, suffer from the remotely exploitable vulnerability, discovered by Eran Goldstein of CRITIFENCE.

Improper implementation of the network configuration module in UMAS protocol may allow an attacker to intercept a target PLC’s network traffic by remotely modifying configuration parameters.

CVE-2018-7798 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 8.2.

The product sees use mainly in the commercial facilities sector on a global basis.

No known public exploits specifically target this vulnerability. An attacker, however, would need a low skill level to exploit the vulnerability.

Schneider Electric recommends the following mitigations to reduce the risk:
• Set up a firewall blocking all remote/external access to Port 502.
• Within the Modicon M221 application, users should disable all unused protocols, especially programming protocol, as described in section “Configuring Ethernet Network” of SoMachine Basic online help. This will prevent remote programming of the M221 PLC.

Click here for Schneider Electric’s security notice SEVD-2018-270-01.

Schneider Electric also recommends the following industry cybersecurity practices:
• Locate control and safety system networks and remote devices behind firewalls, and isolate them from the business network.
• Physical controls should be in place so that no unauthorized person would have access to the ICS and safety controllers, peripheral equipment or the ICS and safety networks.
• All controllers should reside in locked cabinets and never be left in the “Program” mode.
• All programming software should be kept in locked cabinets and should never be connected to any network other than the network for the devices that it is intended.
• All methods of mobile data exchange with the isolated network such as CDs, USB drives, etc., should be scanned before use in the terminals or any node connected to these networks.
• Laptops that have connected to any other network besides the intended network should never be allowed to connect to the safety or control networks without proper sanitation.
• Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
• 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.



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