CVE-2018-3926 in SmartThings Hub STH-ETH-250
Summary
by MITRE
An exploitable integer underflow vulnerability exists in the ZigBee firmware update routine of the hubCore binary of the Samsung SmartThings Hub STH-ETH-250 - Firmware version 0.20.17. The hubCore process incorrectly handles malformed files existing in its data directory, leading to an infinite loop, which eventually causes the process to crash. An attacker can send an HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability described in CVE-2018-3926 represents a critical integer underflow condition within the firmware update mechanism of the Samsung SmartThings Hub STH-ETH-250 device. This flaw manifests specifically within the hubCore binary process that manages ZigBee firmware updates, creating a dangerous scenario where malformed file handling can lead to system instability and potential denial of service conditions. The vulnerability exists in firmware version 0.20.17, indicating this was a known issue that required remediation through proper software updates. The integer underflow occurs during the processing of files within the device's data directory, where the system fails to properly validate the bounds of integer operations, leading to unexpected behavior in the firmware update routine.
The technical exploitation of this vulnerability involves an attacker sending a specially crafted HTTP request to the affected device, which triggers the malformed file processing path within the hubCore binary. When the system encounters these malformed files, the integer underflow causes the firmware update routine to enter an infinite loop state, where the system continuously processes the same invalid data without proper termination conditions. This infinite loop eventually leads to the complete crash of the hubCore process, effectively rendering the device's firmware update functionality non-operational and potentially compromising the overall security posture of the smart home network. The vulnerability demonstrates a classic lack of input validation and proper boundary checking in the firmware update handling code.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential attack vector that could be leveraged to disrupt smart home operations and compromise the integrity of the connected IoT ecosystem. When the hubCore process crashes, it affects the entire SmartThings hub's ability to manage ZigBee devices, potentially leaving users unable to control their connected smart home appliances. The infinite loop condition could also consume significant system resources, leading to broader performance degradation that might affect other network services. This vulnerability directly relates to CWE-191, which describes integer underflow conditions, and can be mapped to ATT&CK technique T1210, involving exploitation of remote services through HTTP requests. The attack surface is particularly concerning as it requires minimal privileges to exploit, making it accessible to attackers who can simply send HTTP requests to the device's network interface.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from Samsung to address the integer underflow condition in the hubCore binary. Network segmentation and access controls should be implemented to limit direct HTTP access to the SmartThings hub, reducing the attack surface available to potential exploiters. Regular monitoring of the device's process health and implementation of automated alerting systems can help detect when the hubCore process enters an abnormal state. Organizations should also consider implementing network intrusion detection systems that can identify and block suspicious HTTP requests targeting known vulnerable endpoints. The vulnerability highlights the importance of proper input validation and boundary checking in embedded firmware systems, emphasizing that IoT device manufacturers must implement comprehensive security testing procedures before releasing firmware updates to production environments.