CVE-2024-37036: Schneider Electric Sage RTU Auth Bypass

CVE-2024-37036 Overview

CVE-2024-37036 is an out-of-bounds write vulnerability [CWE-787] affecting Schneider Electric Sage Remote Terminal Unit (RTU) firmware. The flaw allows an attacker to bypass authentication by sending a malformed HTTP POST request when specific configuration parameters are enabled. The vulnerability is exploitable remotely over the network, requires no authentication, and needs no user interaction. Affected devices include the Sage 1410, 1430, 1450, 2400, 3030 Magnum, and 4400 RTU product lines used in industrial and utility control environments.

Critical Impact
Successful exploitation grants unauthenticated network attackers the ability to bypass authentication on industrial RTU devices, threatening the confidentiality, integrity, and availability of operational technology assets.

Affected Products

Schneider Electric Sage RTU Firmware
Schneider Electric Sage 1410, 1430, 1450
Schneider Electric Sage 2400, 3030 Magnum, 4400

Discovery Timeline

2024-06-12 - CVE-2024-37036 published to the National Vulnerability Database
2024-11-21 - Last updated in the NVD database

Technical Details for CVE-2024-37036

Vulnerability Analysis

The vulnerability resides in the HTTP request handling logic of the Sage RTU firmware. The device fails to properly validate the size or structure of data fields within a POST request before writing them to a fixed-size buffer. When particular configuration parameters are enabled on the RTU, this missing boundary check allows attacker-supplied data to overwrite adjacent memory regions.

The out-of-bounds write [CWE-787] corrupts memory used by the authentication routine. By crafting the malformed request precisely, an attacker can manipulate program state so that authentication checks succeed without valid credentials. The condition is reachable over the network with no prior access to the device.

The Sage RTU family operates in substation automation, SCADA, and remote telemetry roles. Authentication bypass on these devices exposes engineering interfaces, configuration data, and control logic to manipulation by remote adversaries.

Root Cause

The root cause is insufficient input validation in the firmware's HTTP POST request parser. Attacker-controlled length or content fields are written to memory without enforcing buffer boundaries, producing an out-of-bounds write that overlaps memory used to track authentication state.

Attack Vector

An unauthenticated remote attacker reachable over the network sends a crafted POST request to the management interface of a Sage RTU configured with the susceptible parameters. The malformed payload triggers the out-of-bounds write and bypasses authentication. No social engineering, prior credentials, or local access are required. See the Schneider Electric Security Notice SEVD-2024-163-05 for vendor-supplied technical details.

Detection Methods for CVE-2024-37036

Indicators of Compromise

Unexpected HTTP POST requests to Sage RTU management interfaces from external or non-engineering source addresses.
Anomalous POST payloads containing oversized fields, malformed headers, or non-standard content lengths.
Authenticated sessions or configuration changes on RTUs without corresponding operator activity in change-management records.

Detection Strategies

Inspect north-south and east-west traffic to RTU management ports using deep packet inspection tuned for ICS HTTP traffic patterns.
Baseline normal engineering workstation interactions with Sage RTUs and alert on deviations in source, frequency, or payload size.
Correlate firmware-side audit logs with network capture data to identify session establishments that lack matching authentication events.

Monitoring Recommendations

Forward RTU syslog and audit data into a centralized SIEM for retention and correlation.
Monitor for configuration parameter changes that enable the vulnerable POST handling path.
Track outbound connections from RTU subnets that could indicate post-exploitation pivoting into the OT environment.

How to Mitigate CVE-2024-37036

Immediate Actions Required

Apply the Schneider Electric firmware update referenced in SEVD-2024-163-05 to all affected Sage RTU devices.
Inventory Sage 1410, 1430, 1450, 2400, 3030 Magnum, and 4400 deployments and confirm firmware versions against the vendor advisory.
Restrict network access to RTU management interfaces to engineering workstations on isolated OT networks.

Patch Information

Schneider Electric has published remediation guidance in security notice SEVD-2024-163-05. Operators should consult the advisory for fixed firmware versions, upgrade procedures, and product-specific mitigations. Patching industrial RTUs typically requires coordinated maintenance windows and validation against control system integrity.

Workarounds

Disable the configuration parameters that enable the vulnerable POST handler if operationally feasible until patches are applied.
Place affected RTUs behind firewalls and ICS-aware gateways that block unauthorized HTTP traffic to device management ports.
Enforce network segmentation between corporate IT and OT zones following IEC 62443 zone and conduit guidance.
Require VPN with multi-factor authentication for any remote engineering access to RTU networks.

bash

# Configuration example: restrict HTTP access to Sage RTU management interface
# Replace RTU_IP and ENGINEERING_NET with environment-specific values
iptables -A FORWARD -p tcp -s ENGINEERING_NET -d RTU_IP --dport 80 -j ACCEPT
iptables -A FORWARD -p tcp -d RTU_IP --dport 80 -j DROP