CVE-2025-11781 Overview
CVE-2025-11781 is a high-severity firmware vulnerability affecting Circutor SGE-PLC1000 and SGE-PLC50 programmable logic controllers running firmware version 9.0.2. The vulnerability stems from the use of hardcoded cryptographic keys within the affected firmware, allowing attackers with local access to extract authentication keys and create valid firmware update packages, effectively bypassing all intended access controls.
This hardcoded credentials vulnerability (CWE-321) represents a significant security risk for industrial control systems and energy management deployments utilizing these Circutor devices. Successful exploitation grants attackers full administrative privileges over the affected PLCs, potentially enabling complete system compromise.
Critical Impact
Attackers can extract hardcoded authentication keys to create malicious firmware packages, gaining full administrative control over industrial PLCs and bypassing all security controls.
Affected Products
- Circutor SGE-PLC1000 Firmware v9.0.2
- Circutor SGE-PLC1000 Hardware
- Circutor SGE-PLC50 Firmware v9.0.2
- Circutor SGE-PLC50 Hardware
Discovery Timeline
- December 2, 2025 - CVE-2025-11781 published to NVD
- December 3, 2025 - Last updated in NVD database
Technical Details for CVE-2025-11781
Vulnerability Analysis
The vulnerability carries a CVSS 4.0 base score of 8.6 (High) with the following vector string:
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Key metrics indicate:
- Attack Vector: Local - requires physical or local system access
- Attack Complexity: Low - exploitation is straightforward once access is achieved
- Privileges Required: None - no authentication needed to extract the key
- User Interaction: None - exploitation can be fully automated
- Impact: High confidentiality, integrity, and availability impact on the vulnerable system
The EPSS (Exploit Prediction Scoring System) data shows a probability of 0.018% with a percentile ranking of 3.98, indicating relatively low current exploitation likelihood in the wild.
Root Cause
The root cause of CVE-2025-11781 is the implementation of a hardcoded static authentication key within the firmware of Circutor SGE-PLC devices. This cryptographic key management flaw (CWE-321: Use of Hard-coded Cryptographic Key) violates fundamental secure development practices by embedding static credentials directly into the firmware image.
When authentication keys are hardcoded rather than dynamically generated or securely provisioned, they become discoverable through firmware analysis techniques. Once extracted, these keys can be used across all devices running the same firmware version, as the key is identical for every installation.
Attack Vector
The attack requires local access to the target device, which can be achieved through:
- Physical Access: Direct connection to the PLC hardware to dump firmware or memory contents
- Firmware Image Analysis: Obtaining the firmware update package and performing reverse engineering to locate the embedded authentication key
- Memory Dump Extraction: Reading device memory through debug interfaces or other local access methods
Once the hardcoded authentication key is extracted, an attacker can:
- Create legitimate-appearing firmware update packages
- Sign malicious firmware with the extracted key
- Deploy compromised firmware to target devices
- Gain full administrative privileges over the PLC
- Potentially pivot to attack connected industrial systems
The vulnerability exploitation does not require creating synthetic code examples. The attack methodology involves standard firmware reverse engineering techniques using tools like binwalk, Ghidra, or IDA Pro to analyze the firmware binary and locate hardcoded cryptographic material. For detailed technical information, refer to the INCIBE-CERT advisory linked in the references section.
Detection Methods for CVE-2025-11781
Indicators of Compromise
- Unexpected firmware updates or version changes on SGE-PLC1000/SGE-PLC50 devices
- Unauthorized access to device administrative interfaces
- Anomalous network traffic patterns to/from PLC devices
- Configuration changes not initiated by authorized personnel
- Evidence of firmware extraction attempts or debug interface access
Detection Strategies
Organizations should implement comprehensive monitoring for their Circutor PLC deployments:
- Firmware Integrity Monitoring: Establish baseline firmware hashes and regularly verify device firmware integrity against known-good values
- Access Logging: Enable and centralize logging for all administrative access to PLC devices
- Network Segmentation Monitoring: Monitor traffic crossing industrial network boundaries for unauthorized firmware transfer attempts
- Physical Security Auditing: Review physical access logs for unauthorized entry to areas housing PLC equipment
SentinelOne Singularity provides endpoint detection capabilities that can identify suspicious activities on systems with network visibility to OT/ICS environments. The platform's behavioral AI can detect anomalous access patterns and potential lateral movement toward industrial control systems.
Monitoring Recommendations
- Deploy network monitoring at industrial control system boundaries
- Implement asset inventory tracking for all PLC firmware versions
- Configure alerts for firmware modification attempts
- Establish change management procedures requiring verification of firmware updates
- Monitor for tools commonly used in firmware reverse engineering (binwalk, Ghidra) on systems with access to OT networks
How to Mitigate CVE-2025-11781
Immediate Actions Required
- Inventory all Circutor SGE-PLC1000 and SGE-PLC50 devices running firmware version 9.0.2
- Restrict physical and network access to affected PLCs to authorized personnel only
- Implement network segmentation to isolate affected devices from untrusted networks
- Monitor affected devices for unauthorized firmware changes or configuration modifications
- Contact Circutor for updated firmware availability and patch timeline
Patch Information
Organizations should consult the INCIBE-CERT security advisory for the latest information on available patches and remediation guidance:
Monitor vendor communications for firmware updates that address the hardcoded cryptographic key vulnerability. When patches become available, follow vendor guidelines for secure firmware update procedures.
Workarounds
Until a vendor patch is available, implement the following compensating controls:
- Network Isolation: Place affected PLCs on isolated network segments with strict access controls
- Physical Security: Restrict physical access to device locations and implement access logging
- Monitoring: Deploy enhanced monitoring for any access attempts to affected devices
- Firmware Verification: Establish procedures to verify firmware integrity before and after any maintenance activities
- Access Control Lists: Implement strict firewall rules limiting which systems can communicate with affected PLCs
For industrial environments, consider implementing defense-in-depth strategies that include network monitoring solutions capable of detecting anomalous traffic patterns and unauthorized access attempts to OT/ICS devices.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
