CVE-2018-3909 in SmartThings Hub STH-ETH-250
Summary
by MITRE
An exploitable vulnerability exists in the REST parser of video-core's HTTP server of the Samsung SmartThings Hub STH-ETH-250 - Firmware version 0.20.17. The video-core process incorrectly handles pipelined HTTP requests, which allows successive requests to overwrite the previously parsed HTTP method, 'onmessagecomplete' callback. An attacker can send an HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 05/04/2023
The vulnerability identified as CVE-2018-3909 represents a critical buffer overread condition within the REST parser component of Samsung SmartThings Hub STH-ETH-250 firmware version 0.20.17. This issue manifests specifically within the video-core HTTP server process where the system fails to properly manage pipelined HTTP requests. The flaw stems from improper handling of request sequencing that allows subsequent requests to overwrite memory locations containing previously parsed HTTP method information. The vulnerability is particularly concerning as it affects the core communication mechanism of the smart home hub, potentially enabling remote code execution or denial of service conditions. This type of memory corruption vulnerability falls under CWE-121 which describes stack-based buffer overflow conditions, though the specific implementation involves heap memory manipulation through improper request processing.
The technical exploitation of this vulnerability occurs through carefully crafted pipelined HTTP requests that manipulate the parser's state machine. When multiple HTTP requests are sent in sequence without proper separation, the video-core process fails to maintain distinct state information for each request. The 'onmessagecomplete' callback function becomes corrupted as successive requests overwrite the memory location containing the method information from previous requests. This creates a scenario where an attacker can manipulate the control flow of the HTTP server by injecting malicious request data that overwrites the callback function pointer or related state variables. The vulnerability is classified under the ATT&CK technique T1210 which describes exploitation of remote services through malformed input, specifically targeting HTTP server implementations.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable complete system compromise. An attacker who successfully exploits this vulnerability could gain unauthorized access to the SmartThings Hub, potentially allowing them to control connected smart home devices, access network traffic, or use the device as a pivot point for attacking other systems within the local network. The attack vector requires only network connectivity to the hub's HTTP server, making it particularly dangerous in residential or commercial environments where physical security may be limited. The vulnerability affects the firmware version 0.20.17 specifically, indicating that Samsung may have addressed similar issues in subsequent releases through proper memory management and request parsing improvements.
Mitigation strategies for CVE-2018-3909 should focus on immediate firmware updates from Samsung to address the root cause of the memory handling issue. Network segmentation and firewall rules can help limit access to the SmartThings Hub's HTTP server, reducing the attack surface for potential exploitation. Additionally, monitoring network traffic for unusual pipelined HTTP request patterns may help detect attempted exploitation of this vulnerability. Security teams should implement regular firmware update policies and consider disabling unnecessary HTTP services on smart home devices when possible. The vulnerability highlights the importance of proper input validation and memory management in embedded systems, particularly those handling network communications. Organizations should also consider implementing intrusion detection systems specifically configured to detect malformed HTTP request patterns that could indicate exploitation attempts.