CVE-2020-7534 – This CSRF vulnerability in Schneider Electric M... (How to Fix)

Q: What is the severity of CVE-2020-7534?

CVE-2020-7534 has a CVSS score of 8.8 (HIGH). This CSRF vulnerability in Schneider Electric Modicon PLCs allows attackers to trick authenticated users into performing unauthorized actions or leaking sensitive data. It affects multiple Modicon M340, Quantum, and Premium programmable logic controllers with integrated Ethernet modules. The vulnerability exists while users are logged into the web interface.

📋 TL;DR

This CSRF vulnerability in Schneider Electric Modicon PLCs allows attackers to trick authenticated users into performing unauthorized actions or leaking sensitive data. It affects multiple Modicon M340, Quantum, and Premium programmable logic controllers with integrated Ethernet modules. The vulnerability exists while users are logged into the web interface.

💻 Affected Systems

Products:

Modicon M340 CPUs: BMXP34
Modicon Quantum CPUs: 140CPU65
Modicon Premium CPUs: TSXP57
Modicon M340 ethernet modules: BMXNOC0401, BMXNOE01, BMXNOR0200H
Modicon Quantum and Premium factory cast communication modules: 140NOE77111, 140NOC78*00, TSXETY5103, TSXETY4103

Versions: All Versions

Operating Systems: Embedded firmware on PLCs

Default Config Vulnerable: ⚠️ Yes

Notes: Affects web server components on these industrial control devices. Requires user to be authenticated to the web interface.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of industrial control system allowing unauthorized configuration changes, data exfiltration, or disruption of industrial processes.

🟠

Likely Case

Unauthorized configuration changes to PLCs leading to operational disruption or data leakage from the web interface.

🟢

If Mitigated

Limited impact with proper network segmentation and CSRF protections in place.

🌐 Internet-Facing: HIGH - Direct internet exposure would allow remote attackers to exploit this vulnerability.

🏢 Internal Only: MEDIUM - Requires internal attacker or compromised internal system to exploit.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: LOW

CSRF attacks typically have low complexity but require the victim to be authenticated. No public exploit code identified.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Refer to vendor advisory for specific firmware updates

Vendor Advisory: https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2022-011-01

Restart Required: Yes

Instructions:

1. Review Schneider Electric advisory SEVD-2022-011-01. 2. Download appropriate firmware updates from Schneider Electric. 3. Apply firmware updates to affected devices following vendor procedures. 4. Restart devices as required.

🔧 Temporary Workarounds

Network Segmentation

all

Isolate affected PLCs from untrusted networks and limit access to authorized personnel only.

CSRF Token Implementation

all

Implement anti-CSRF tokens in web applications that interact with these PLCs.

🧯 If You Can't Patch

Implement strict network segmentation to isolate affected devices
Use browser extensions that block CSRF attacks and enforce same-origin policies

🔍 How to Verify

Check if Vulnerable:

Check device firmware version against vendor advisory. Devices with affected firmware versions are vulnerable.

Check Version:

Check firmware version through device web interface or programming software (Unity Pro, EcoStruxure Control Expert)

Verify Fix Applied:

Verify firmware version has been updated to patched version specified in vendor advisory.

📡 Detection & Monitoring

Log Indicators:

Unexpected configuration changes in PLC logs
Multiple failed authentication attempts followed by successful login

Network Indicators:

Unusual HTTP requests to PLC web interfaces from unexpected sources
CSRF-like request patterns

SIEM Query:

source="plc_web_logs" AND (action="configuration_change" OR status="unauthorized")

📊 Metadata

CVE ID: CVE-2020-7534

CVSS v3 Score: 8.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-352

Published: February 4, 2022

Last Updated: November 21, 2024

🔗 References

https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2022-011-01 Patch,Vendor Advisory
https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2022-011-01 Patch,Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2020-7534, you might also want to check these: