CVE-2023-25619 – This vulnerability allows attackers to cause de... (How to Fix)

Q: What is the severity of CVE-2023-25619?

CVE-2023-25619 has a CVSS score of 7.5 (HIGH). This vulnerability allows attackers to cause denial of service on Schneider Electric controllers by sending specially crafted Modbus TCP packets that trigger improper exception handling. It affects industrial control systems using vulnerable Schneider Electric products with Modbus TCP communication enabled.

📋 TL;DR

This vulnerability allows attackers to cause denial of service on Schneider Electric controllers by sending specially crafted Modbus TCP packets that trigger improper exception handling. It affects industrial control systems using vulnerable Schneider Electric products with Modbus TCP communication enabled.

💻 Affected Systems

Products:

Schneider Electric controllers with Modbus TCP functionality

Versions: Specific versions not provided in CVE description; refer to vendor advisory for details

Operating Systems: Embedded/RTOS systems on affected controllers

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with Modbus TCP enabled; systems using other protocols or with Modbus disabled are not vulnerable.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete controller shutdown requiring physical reset, disrupting industrial processes and potentially causing safety incidents or production downtime.

🟠

Likely Case

Temporary controller unresponsiveness requiring manual restart, causing operational disruption but not permanent damage.

🟢

If Mitigated

No impact if proper network segmentation and input validation are implemented.

🌐 Internet-Facing: HIGH - Modbus TCP is often exposed and lacks authentication, making internet-facing systems particularly vulnerable.

🏢 Internal Only: MEDIUM - Internal systems are still vulnerable but require network access, reducing exposure compared to internet-facing systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Modbus TCP typically lacks authentication, making exploitation straightforward once the vulnerability details are known.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Refer to Schneider Electric advisory SEVD-2023-101-05 for specific patched versions

Vendor Advisory: https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2023-101-05&p_enDocType=Security+and+Safety+Notice&p_File_Name=SEVD-2023-101-05.pdf

Restart Required: Yes

Instructions:

1. Download firmware update from Schneider Electric portal. 2. Apply update following vendor documentation. 3. Restart controller. 4. Verify patch installation.

🔧 Temporary Workarounds

Network Segmentation

linux

Isolate Modbus TCP traffic to trusted networks only

iptables -A INPUT -p tcp --dport 502 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 502 -j DROP

Disable Modbus TCP

all

Turn off Modbus TCP if not required for operations

Refer to controller configuration manual for disable commands

🧯 If You Can't Patch

Implement strict network access controls to limit Modbus TCP traffic to authorized sources only
Deploy intrusion detection systems to monitor for anomalous Modbus traffic patterns

🔍 How to Verify

Check if Vulnerable:

Check controller firmware version against vendor advisory; test with controlled Modbus TCP packets if possible

Check Version:

Refer to controller documentation for version check command (varies by product)

Verify Fix Applied:

Verify firmware version matches patched version from advisory; test with previously crashing Modbus packets

📡 Detection & Monitoring

Log Indicators:

Controller restart logs
Modbus TCP connection errors
Unexpected controller resets

Network Indicators:

Unusual Modbus TCP traffic patterns
Multiple connection attempts to port 502
Malformed Modbus packets

SIEM Query:

source="controller_logs" AND (event="restart" OR event="crash") AND protocol="modbus_tcp"

📊 Metadata

CVE ID: CVE-2023-25619

CVSS v3 Score: 7.5 (HIGH)

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

CWE: CWE-754

Published: April 19, 2023

Last Updated: February 5, 2025

🔗 References

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