CVE-2024-37040 Overview
CVE-2024-37040 is a classic buffer overflow vulnerability [CWE-120] affecting Schneider Electric Sage Remote Terminal Unit (RTU) firmware. The flaw exists in the device's web interface, which fails to validate the size of input received in HTTP requests. An authenticated attacker with access to the web interface can send a malformed HTTP request to trigger a device fault, disrupting operational technology (OT) processes controlled by these industrial devices.
Critical Impact
Successful exploitation causes a denial of service and potential integrity impact on Schneider Electric Sage RTUs deployed in critical infrastructure environments such as electric utilities and industrial control systems.
Affected Products
- Schneider Electric Sage RTU Firmware
- Schneider Electric Sage 1410, Sage 1430, Sage 1450
- Schneider Electric Sage 2400, Sage 3030 Magnum, Sage 4400
Discovery Timeline
- 2024-06-12 - CVE-2024-37040 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-37040
Vulnerability Analysis
The vulnerability resides in the HTTP request handling logic of the Sage RTU web interface. The firmware copies attacker-supplied input from an HTTP request into a fixed-size buffer without verifying that the input length fits within the allocated space. When an oversized field is supplied, adjacent memory is overwritten, causing the device to enter a fault state.
Because the affected devices are Remote Terminal Units used to monitor and control substation equipment, a fault condition interrupts telemetry, supervisory control, and automated protection logic. Exploitation requires network access to the management interface and valid low-privilege credentials on the device.
Root Cause
The root cause is missing bounds checking during input copy operations in the web server component. The firmware invokes an unbounded memory copy against user-controlled HTTP request data. This maps directly to CWE-120: Buffer Copy without Checking Size of Input.
Attack Vector
An attacker authenticates to the web interface and issues a crafted HTTP request containing an oversized parameter, header, or body field. Processing the request corrupts memory and forces the RTU into a fault state. No user interaction is required beyond the attacker's authenticated session.
Refer to the Schneider Electric Security Notice SEVD-2024-163-05 for vendor technical details.
Detection Methods for CVE-2024-37040
Indicators of Compromise
- Unexpected reboots, faults, or watchdog resets on Sage 1410, 1430, 1450, 2400, 3030 Magnum, or 4400 RTUs.
- HTTP requests to the RTU web interface containing abnormally long headers, URIs, or form fields.
- Loss of SCADA telemetry or control response from an affected RTU coinciding with web interface activity.
Detection Strategies
- Inspect network traffic to the RTU management interface for HTTP requests exceeding expected field lengths.
- Correlate authentication events on the web interface with subsequent device fault or restart events.
- Baseline normal HTTP interaction patterns with the RTU and alert on deviations, including unusual source IPs on the OT network.
Monitoring Recommendations
- Forward RTU syslog and SCADA historian events into a centralized logging platform for cross-correlation.
- Monitor OT network segments with an industrial intrusion detection system tuned for Schneider Electric protocols and HTTP anomalies.
- Alert on any web interface access originating from outside authorized engineering workstations or jump hosts.
How to Mitigate CVE-2024-37040
Immediate Actions Required
- Apply the firmware update published by Schneider Electric in security notice SEVD-2024-163-05.
- Restrict network access to the RTU web interface using firewalls and ACLs so only authorized engineering workstations can reach it.
- Enforce strong, unique credentials on every RTU and rotate any shared or default accounts.
- Segment RTUs onto a dedicated OT network zone isolated from corporate IT and internet-facing systems.
Patch Information
Schneider Electric released remediation guidance in SEVD-2024-163-05. Operators should review the notice for fixed firmware versions applicable to each Sage RTU model and follow Schneider Electric's recommended upgrade procedure during a planned maintenance window.
Workarounds
- Disable the web interface on RTUs where it is not required for operations.
- Place the RTU behind a VPN or bastion host that terminates HTTPS and applies request-size limits.
- Implement network intrusion prevention rules that drop HTTP requests to the RTU containing oversized headers or fields.
- Follow Schneider Electric's published cybersecurity best practices for Sage RTU deployments until patching is complete.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
