Schneider Electric Modicon PLCs Use of Insufficiently Random Values (CVE-2017-6026)

critical Tenable OT Security Plugin ID 500862

Synopsis

The remote OT asset is affected by a vulnerability.

Description

A Use of Insufficiently Random Values issue was discovered in Schneider Electric Modicon PLCs Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The session numbers generated by the web application are lacking randomization and are shared between several users. This may allow a current session to be compromised.

This plugin only works with Tenable.ot.
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Solution

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

Schneider Electric has released new firmware versions to address the predictable value range from previous values vulnerability and the use of insufficiently random values vulnerability, which are available through Schneider Electric’s software update tool, SoMachine, Version 4.2, and SoMachineBasic, Version 1.5. Schneider Electric has not released a product to address the insufficiently protected credentials vulnerability; however, Schneider Electric has provided compensating controls to reduce the risk of exploitation.

SoMachineBasic, Version 1.5, is available at the following location:

http://www.schneider-electric.fr/fr/download/document/SOMBASAP15SOFT/

Schneider Electric has provided the following compensating controls to reduce the risk of exploitation of the insufficiently protected credentials vulnerability:

- Verify that the hardware and software infrastructure that the PLCs are integrated into (along with all organizational measures and rules covering access to the infrastructure) consider the results of the hazard and risk analysis, and are implemented according to best practices and standards such as ISA/IEC 62443.
- Limit traffic on the local network with managed switches
- Where possible, avoid using Wi-Fi networks, but when Wi-Fi is essential, use only secure communications (such as WPA2 encryption)
- Do not grant [network] access to unknown computers
- When remote access is essential, use secure methods such as Virtual Private Networks (VPNs), and ensure the remote access solution(s), as well as the remote computer(s) are kept up-to-date with the latest security patches.

Schneider Electric has released Security Notifications SEVD-2017-075-01, SEVD-2017-075-02, and SEVD-2017-075-03, which provide additional information about the identified vulnerabilities, mitigations, and compensating controls:

http://www.schneider-electric.com/en/download/document/SEVD-2017-075-01/

http://www.schneider-electric.com/en/download/document/SEVD-2017-075-02/

http://www.schneider-electric.com/en/download/document/SEVD-2017-075-03/

Plugin Details

Severity: Critical

ID: 500862

Version: 1.7

Type: remote

Family: Tenable.ot

Published: 3/1/2023

Updated: 3/4/2024

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: Medium

Base Score: 6.4

Temporal Score: 5

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

CVSS Score Source: CVE-2017-6026

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 8.2

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

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

Vulnerability Information

CPE: cpe:/o:schneider-electric:modicon_m241_series_firmware, cpe:/o:schneider-electric:modicon_m251_series_firmware

Required KB Items: Tenable.ot/Schneider

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/30/2017

Vulnerability Publication Date: 6/30/2017

Reference Information

CVE: CVE-2017-6026

CWE: 330

Detections

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