CVE-2018-3873 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 128 bytes. An attacker can send an arbitrarily long "secretKey" value in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability identified as CVE-2018-3873 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 handling mechanism where the system fails to properly validate input lengths before copying data into fixed-size buffers. The specific technical implementation involves the use of strncpy function which, 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. This particular implementation flaw creates a scenario where attackers can manipulate the destination buffer of exactly 128 bytes through crafted input.
The operational impact of this vulnerability extends beyond simple buffer overflow consequences as it provides attackers with a potential path for arbitrary code execution within the device's operational environment. When an attacker sends a specially crafted "secretKey" value exceeding the buffer capacity, the overflow can overwrite adjacent memory locations including return addresses, function pointers, or other critical control data structures. This memory corruption directly enables attackers to manipulate program execution flow and potentially achieve complete system compromise. The vulnerability is particularly concerning in IoT environments where devices often operate with minimal security controls and may serve as entry points for broader network infiltration.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-121, which describes stack-based buffer overflow conditions, and aligns with ATT&CK technique T1210 for exploitation of remote services. The flaw demonstrates poor input validation practices and improper memory management, characteristics commonly found in insecure coding patterns that violate secure software development principles. The specific nature of the vulnerability suggests that the firmware developers failed to implement proper bounds checking or input sanitization mechanisms before invoking the strncpy function. The 128-byte buffer size indicates a design decision that may have been insufficient for the expected input parameters, particularly considering that the secretKey field could theoretically accept arbitrary length values without proper validation.
Mitigation strategies for this vulnerability should encompass multiple layers of defense including immediate firmware updates from Samsung to address the specific buffer overflow condition, network segmentation to limit exposure of affected devices, and implementation of intrusion detection systems to monitor for suspicious credential handling patterns. Organizations should also consider disabling unnecessary HTTP services where possible and implementing strict access controls for the SmartThings Hub. The vulnerability highlights the importance of proper secure coding practices and emphasizes that even seemingly benign functions like strncpy require careful consideration of boundary conditions and input validation. Additionally, regular security assessments of IoT device firmware should be conducted to identify similar insecure coding patterns that could lead to similar exploitable conditions.