CVE-2018-3907 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, 'on_url' 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-2018-3907 represents a critical flaw in the Samsung SmartThings Hub STH-ETH-250 device firmware version 0.20.17. This issue resides within the video-core process's HTTP server implementation and specifically targets the REST parser component that handles incoming HTTP requests. The vulnerability stems from improper handling of pipelined HTTP requests, where multiple requests are sent sequentially without waiting for responses, creating a scenario where subsequent requests can interfere with the processing of earlier ones. This particular weakness manifests when the HTTP server processes multiple requests in rapid succession, causing the system to overwrite critical parsing state information. The flaw allows an attacker to manipulate the HTTP method handling mechanism, specifically targeting the 'on_url' callback function that processes URL parsing during request processing. This vulnerability operates at the application layer of the network stack and can be exploited through standard network communication protocols without requiring physical access or specialized equipment. The issue fundamentally compromises the integrity of HTTP request processing within the device's embedded web server, creating potential for unauthorized access and system manipulation.
The technical implementation of this vulnerability involves a classic buffer overread or state corruption issue within the HTTP request parsing logic. When multiple HTTP requests are pipelined to the affected Samsung SmartThings Hub, the video-core process fails to properly maintain separate state contexts for each request. The system's REST parser incorrectly manages memory structures and callback execution sequences, allowing the processing of one request to overwrite data structures that should remain isolated for previous requests. This memory management flaw specifically affects how the HTTP method information is stored and retrieved during the parsing process, particularly when the 'on_url' callback function is invoked. The vulnerability can be triggered by sending a specially crafted sequence of HTTP requests to the device's HTTP server port, where the second request in the pipeline overwrites the method information from the first request, potentially allowing an attacker to manipulate the server's behavior. This type of vulnerability is categorized under CWE-121, which deals with stack-based buffer overflow conditions, and also relates to CWE-129, concerning improper validation of array indices. The attack pattern aligns with techniques described in the ATT&CK framework under T1059.007 for application layer protocol manipulation and T1071.004 for application layer protocol traffic filtering.
The operational impact of CVE-2018-3907 extends beyond simple denial of service conditions, as it potentially enables full system compromise of the Samsung SmartThings Hub device. An attacker who successfully exploits this vulnerability could gain unauthorized access to the device's internal systems, potentially allowing for remote code execution, data exfiltration, or manipulation of connected smart home devices. The vulnerability affects the core network communication functionality of the device, which serves as a central hub for managing smart home automation systems, making it particularly dangerous in residential and commercial environments. The exploitation requires only network connectivity to the device and can be performed from external networks without requiring physical access or advanced technical skills. This makes the vulnerability particularly concerning as it can be exploited by threat actors with minimal resources and technical expertise. The impact is amplified by the fact that the SmartThings Hub typically operates within home networks and may have access to sensitive personal data, connected IoT devices, and potentially network infrastructure information. The device's role as a central controller for smart home ecosystems means that successful exploitation could lead to cascading security failures affecting multiple connected devices and systems within the network.
Mitigation strategies for CVE-2018-3907 should focus on both immediate device-level protections and long-term architectural improvements. The most effective immediate solution involves updating the device firmware to a version that properly handles pipelined HTTP requests and implements proper state isolation between concurrent requests. Samsung released firmware updates addressing this vulnerability, and users should immediately apply these patches when available. Network-level protections should include implementing firewall rules that restrict access to the SmartThings Hub's HTTP server ports from untrusted networks, and deploying intrusion detection systems that can monitor for suspicious HTTP request patterns. The device should be configured to disable HTTP pipelining if possible, as this feature directly contributes to the vulnerability exploitation. Organizations and individuals should also implement network segmentation to isolate smart home devices from critical network infrastructure, reducing the potential impact of successful exploitation. Additional security measures include monitoring for unusual HTTP request patterns, implementing secure remote access protocols, and regularly auditing network communications to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and state management in embedded systems, particularly those handling network communications. Security teams should consider implementing automated vulnerability scanning tools that can identify similar issues in other networked devices within their environments, as this type of flaw is not unique to Samsung SmartThings hubs but represents a common pattern in embedded HTTP server implementations.