CVE-2018-3877 in SmartThings Hub STH-ETH-250
Summary
by MITRE
An exploitable buffer overflow vulnerability exists in the credentials handler of video-core's HTTP server of Samsung SmartThings Hub STH-ETH-250-Firmware version 0.20.17. The strncpy overflows the destination buffer, which has a size of 160 bytes. An attacker can send an arbitrarily long "directory" value in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability described in CVE-2018-3877 represents a critical buffer overflow flaw within the video-core HTTP server component of Samsung SmartThings Hub STH-ETH-250 devices running firmware version 0.20.17. This issue resides in the credentials handler module, which processes authentication requests from connected devices and users. The flaw stems from improper input validation and memory management practices that allow attackers to manipulate the system's memory layout through crafted HTTP requests. The vulnerability specifically manifests when the system processes directory parameters during credential validation, creating a pathway for arbitrary code execution and complete system compromise.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where the strncpy function is used to copy user-supplied data into a fixed-size buffer of only 160 bytes. This function, while designed to prevent buffer overflows by limiting the number of characters copied, fails to account for the null termination requirement when the source string length equals or exceeds the specified limit. The strncpy implementation does not automatically append a null terminator when the source string is exactly the same length as the specified copy limit, leaving the destination buffer in an inconsistent state. This flaw creates a predictable memory corruption scenario where attackers can overwrite adjacent memory locations with controlled data, potentially including return addresses, function pointers, or other critical program state information.
The operational impact of this vulnerability extends beyond simple denial of service or data corruption, as it enables complete system compromise through remote exploitation. An attacker with network access to the SmartThings Hub can craft malicious HTTP requests containing directory values exceeding 160 bytes to overwrite the buffer and potentially redirect program execution flow. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a direct threat to the integrity and availability of smart home ecosystems. The attack surface is particularly concerning given that SmartThings hubs serve as central control points for home automation networks, making successful exploitation potentially devastating for end-user security and privacy.
Security professionals should note that this vulnerability demonstrates poor input validation practices and highlights the importance of proper memory management in embedded systems. The flaw can be exploited through standard network-based attacks without requiring physical access or specialized equipment, making it particularly dangerous for IoT deployments. Organizations should implement immediate mitigations including firmware updates, network segmentation, and monitoring for suspicious HTTP traffic patterns. The vulnerability also relates to ATT&CK technique T1210, which covers exploitation of remote services, and represents a significant risk to enterprise and home network security infrastructure. Mitigation strategies should include network access controls, regular firmware updates, and comprehensive vulnerability assessments of connected IoT devices to prevent similar issues in other embedded systems.