CVE-2018-3893 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 video-core process incorrectly extracts fields from a user-controlled JSON payload, leading to a buffer overflow on the stack. 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-2018-3893 represents a critical buffer overflow flaw within the Samsung SmartThings Hub STH-ETH-250 device firmware version 0.20.17. This issue resides in the video-core HTTP server component specifically within the /cameras/XXXX/clips handler, which processes incoming requests related to camera clip management. The flaw stems from improper input validation and handling of user-controlled JSON payloads that are processed by the video-core process. When an attacker crafts a malicious JSON request containing oversized or malformed data fields, the system fails to properly bounds-check the incoming data before copying it into fixed-size stack buffers. This fundamental failure in memory management creates a predictable buffer overflow condition that can be exploited to overwrite adjacent stack memory locations. The vulnerability is particularly concerning because it exists in a network-accessible HTTP endpoint, meaning remote exploitation is possible without physical access to the device. The attack surface is further expanded by the fact that the affected handler processes camera clip data, which could potentially include sensitive video content or metadata that an attacker might attempt to manipulate or extract.
The technical implementation of this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which occurs when a program writes more data to a fixed-length buffer than it can hold, typically overwriting adjacent memory locations including return addresses and function parameters. The specific nature of the flaw indicates that the video-core process performs direct string copying operations without proper validation of input lengths, allowing an attacker to overflow the stack buffer and potentially control the instruction pointer. The exploitation requires sending a specially crafted HTTP request to the /cameras/XXXX/clips endpoint, which triggers the vulnerable code path within the video-core process. This attack vector maps to the ATT&CK technique T1203 Exploitation for Client Execution, as the vulnerability enables remote code execution through HTTP request manipulation. The stack-based nature of the overflow means that attackers can potentially overwrite the return address of the function containing the vulnerable buffer, allowing them to redirect execution flow to malicious code. The buffer overflow could also corrupt other stack variables, potentially leading to denial of service or privilege escalation depending on the execution context of the video-core process.
The operational impact of this vulnerability extends beyond simple exploitation, as the Samsung SmartThings Hub serves as a central control point for home automation systems, making it a valuable target for attackers seeking to gain persistent access to home networks. The vulnerability could enable attackers to execute arbitrary code on the device, potentially allowing them to install backdoors, monitor network traffic, or use the hub as a pivot point to attack other devices on the local network. Given that the SmartThings Hub is designed to integrate with various smart home devices, successful exploitation could provide attackers with access to sensitive personal data, including video feeds from connected cameras and information about household activities. The device's role in home automation systems means that attackers could potentially manipulate smart locks, lighting systems, or other connected devices through the compromised hub. The firmware version 0.20.17 indicates this was a relatively recent vulnerability at the time of discovery, suggesting that Samsung had not yet addressed the issue in their update cycle. Network-based exploitation means that attackers do not require physical access to the device, making the attack surface significantly larger than local exploitation methods. The presence of this vulnerability in a device designed for home security and automation creates a particularly dangerous scenario where personal privacy and security are at risk.
Mitigation strategies for CVE-2018-3893 should prioritize immediate firmware updates from Samsung, as the vendor would have likely released a patch addressing the buffer overflow in the video-core process. Network segmentation and firewall rules should be implemented to restrict access to the SmartThings Hub's HTTP endpoints, particularly the vulnerable /cameras/XXXX/clips handler, limiting exposure to unauthorized users. Monitoring network traffic for suspicious HTTP requests targeting the affected endpoint can help detect exploitation attempts before they succeed. The implementation of input validation controls at the network level can provide additional protection by filtering out malformed JSON payloads before they reach the vulnerable application. Security teams should consider disabling unnecessary HTTP endpoints and services on the hub when possible, reducing the attack surface. For environments where immediate patching is not feasible, network-based intrusion detection systems should be configured to detect and alert on patterns consistent with exploitation attempts. Device administrators should also implement regular security assessments to identify other potential vulnerabilities in IoT devices connected to their networks. The vulnerability highlights the importance of secure coding practices, particularly around input validation and memory management, which should be enforced through security development lifecycle processes. Organizations should also consider the broader implications of IoT device security and implement comprehensive policies for managing connected devices in enterprise environments.