CVE-2025-0658 in Zone Controllers
Summary
by MITRE • 11/27/2025
A vulnerability in Automated Logic and Carrier's Zone Controller via BACnet protocol causes the device to crash. The device enters a fault state; after a reset, a second packet can leave it permanently unresponsive until a manual power cycle is performed.
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Analysis
by VulDB Data Team • 11/30/2025
This vulnerability resides within the BACnet protocol implementation of Automated Logic and Carrier's Zone Controller devices, representing a critical fault handling flaw that compromises system availability and operational continuity. The vulnerability manifests as a specific condition where a single malformed or specially crafted BACnet packet can trigger a device crash, forcing the controller into a fault state that persists beyond normal reset procedures. This behavior constitutes a denial of service vulnerability that directly impacts building automation and control systems where these controllers are deployed. The flaw demonstrates poor input validation and error recovery mechanisms within the device's protocol stack, where the system fails to properly handle exceptional conditions during packet processing. The vulnerability's impact extends beyond simple service interruption as it creates a persistent state where the device remains unresponsive even after standard reset procedures, requiring physical intervention to restore functionality.
The technical implementation of this vulnerability involves the BACnet protocol's handling of specific packet structures or sequences that cause the device's state machine to enter an unrecoverable condition. When the malicious packet is received, the controller's processing logic fails to properly manage the error condition, leading to resource exhaustion or memory corruption that prevents normal operation. This type of vulnerability falls under CWE-248, Uncontrolled Format String, or CWE-129, Improper Validation of Array Index, depending on the specific implementation flaw, and represents a failure in robust error handling within industrial control systems. The BACnet protocol's design assumes reliable communication and proper device behavior, but this vulnerability exploits a gap in the protocol's error recovery mechanisms, particularly when dealing with unexpected packet formats or sequences. The vulnerability's exploitation requires minimal network access and can be executed remotely, making it particularly dangerous in networked building automation environments where these controllers are interconnected and managed centrally.
The operational impact of this vulnerability extends far beyond simple device unavailability, creating cascading failures in building automation systems that can affect heating, ventilation, air conditioning, lighting, and other critical environmental controls. When multiple controllers in a building or facility are affected, the vulnerability can lead to widespread environmental control failures, potentially creating unsafe conditions for occupants and compromising sensitive environments such as data centers, laboratories, or healthcare facilities. The requirement for manual power cycling to restore functionality introduces significant operational overhead and risk, as it may require physical access to devices in remote locations or areas where immediate access is difficult or dangerous. This vulnerability particularly affects environments where continuous operation is critical and where manual intervention cannot be quickly coordinated, making it a serious concern for facility managers and industrial control system operators. The vulnerability's persistence across resets aligns with ATT&CK technique T1499.004, Network Denial of Service, and represents a failure in system resilience and fault tolerance that violates fundamental principles of industrial control system design.
Mitigation strategies for this vulnerability must address both immediate operational responses and longer-term architectural improvements. Organizations should implement network segmentation and access controls to limit exposure to unauthorized packet injection, while also establishing monitoring procedures to detect abnormal controller behavior or fault state entries. Device firmware updates should be prioritized, though organizations may need to maintain manual reset procedures and backup protocols during update deployment. Network-based intrusion detection systems can be configured to monitor for anomalous BACnet packet patterns that might indicate exploitation attempts, while also implementing proper access controls and authentication mechanisms for BACnet communications. The vulnerability highlights the need for robust error handling and graceful degradation in industrial control systems, emphasizing the importance of designing systems that can recover from error conditions without requiring physical intervention. Regular vulnerability assessments and penetration testing of building automation systems should be conducted to identify similar weaknesses in other protocol implementations or device controllers, while also ensuring that operational procedures include contingency plans for handling persistent device failures. Organizations should also consider implementing redundant control systems or backup controllers to maintain operational continuity when individual devices become unresponsive.