CVE-2018-3894 in SmartThings Hub STH-ETH-250
Summary
by MITRE
An exploitable buffer overflow vulnerability exists in the /cameras/XXXX/clips handler of video-core's HTTP server of Samsung SmartThings Hub STH-ETH-250-Firmware version 0.20.17. The strncpy call overflows the destination buffer, which has a size of 52 bytes. An attacker can send an arbitrarily long "startTime" value in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability identified as CVE-2018-3894 represents a critical buffer overflow flaw within the Samsung SmartThings Hub STH-ETH-250 firmware version 0.20.17. This issue manifests in the video-core HTTP server component specifically within the /cameras/XXXX/clips handler, where the system fails to properly validate input length before copying data into a fixed-size buffer. The flaw stems from the use of strncpy function without adequate bounds checking, creating a scenario where attacker-controlled input can exceed the allocated buffer space of 52 bytes. This particular endpoint serves as a communication channel for retrieving video clips from connected cameras, making it a prime target for exploitation within the smart home ecosystem.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where the strncpy function, despite its name suggesting safe string copying, does not guarantee null termination when the source string length equals or exceeds the specified maximum length parameter. In this case, the destination buffer size of 52 bytes provides insufficient space for arbitrary "startTime" values that attackers can craft to exceed this limit. The HTTP handler processes requests containing the startTime parameter without proper validation, allowing malicious input to overwrite adjacent memory locations. This behavior directly aligns with CWE-121, which categorizes stack-based buffer overflow conditions, and represents a fundamental failure in input sanitization and memory management practices.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, presenting significant security risks to users of the Samsung SmartThings Hub. An attacker exploiting this flaw could potentially execute arbitrary code on the device, gain unauthorized access to connected camera feeds, or compromise the entire smart home network infrastructure. The vulnerability affects the hub's ability to properly authenticate and validate requests, potentially allowing unauthorized users to access sensitive video data or manipulate camera recording parameters. Given that the SmartThings Hub serves as a central control point for home automation systems, successful exploitation could enable lateral movement within the network and provide attackers with persistent access to the home environment.
Mitigation strategies for CVE-2018-3894 should prioritize immediate firmware updates from Samsung to address the buffer overflow condition in the video-core HTTP server. Network administrators should implement network segmentation to isolate the SmartThings Hub from critical systems and restrict access to the affected HTTP endpoint through firewall rules. Input validation controls should be enhanced at the application level to ensure all parameters passed to the /cameras/XXXX/clips handler are properly bounded and sanitized before processing. Additionally, monitoring systems should be configured to detect unusual patterns in requests to the clips handler, particularly those containing unusually long startTime values that might indicate exploitation attempts. Organizations should also consider implementing intrusion detection systems specifically designed to identify buffer overflow patterns and other common exploitation techniques targeting embedded devices in home automation ecosystems. The vulnerability demonstrates the importance of secure coding practices and input validation in IoT devices, aligning with ATT&CK technique T1059.007 for command and scripting interpreter and T1210 for exploitation of remote services, both of which are relevant to the operational security implications of this flaw.