Schneider Electric Modicon M221 Permissions, Privileges, and Access Controls (CVE-2018-7792)

high Tenable OT Security Plugin ID 500873


The remote OT asset is affected by a vulnerability.


A Permissions, Privileges, and Access Control vulnerability exists in Schneider Electric's Modicon M221 product (all references, all versions prior to firmware V1.6.2.0). The vulnerability allows unauthorized users to decode the password using rainbow table.

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The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at

A fix for these vulnerabilities is implemented in Modicon M221 Firmware v1.6.2.0, delivered within SoMachine Basic v1.6 SP2, which is available for download below, or by using Schneider Electric Software Update tool:

As a temporary mitigation, Modicon M221 users should take the following measures:

- Set up a firewall blocking all remote/external access to Port 502.
- Within the Modicon M221 application, users must 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.

Schneider Electric’s security notice SEVD-2018-235-01 is available at the following location:

See Also

Plugin Details

Severity: High

ID: 500873

Version: 1.6

Type: remote

Family: Tenable.ot

Published: 3/1/2023

Updated: 3/4/2024

Supported Sensors: Tenable OT Security

Risk Information


Risk Factor: Low

Score: 3.6


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS Score Source: CVE-2018-7792


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:schneider-electric:modicon_m221_series_firmware

Required KB Items: Tenable.ot/Schneider

Exploit Ease: No known exploits are available

Patch Publication Date: 8/29/2018

Vulnerability Publication Date: 8/29/2018

Reference Information

CVE: CVE-2018-7792

CWE: 862