CVE-2018-3863 in SmartThings Hub STH-ETH-250
Summary
by MITRE
On Samsung SmartThings Hub STH-ETH-250 devices with 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. A strcpy overflows the destination buffer, which has a size of 40 bytes. An attacker can send an arbitrarily long "user" value in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 05/04/2023
The CVE-2018-3863 vulnerability affects Samsung SmartThings Hub STH-ETH-250 devices running firmware version 0.20.17, representing a critical buffer overflow flaw in the video-core process that handles user-controlled JSON payloads. This vulnerability resides within the device's network services stack and specifically targets the improper handling of input data during JSON parsing operations. The flaw manifests when the system processes HTTP requests containing maliciously crafted JSON content, creating a path for remote code execution through stack-based buffer overflow conditions. The vulnerability is particularly concerning as it operates at the core networking layer of the smart home hub, potentially allowing attackers to compromise the entire device and its connected ecosystem.
The technical implementation of this vulnerability stems from a classic buffer overflow condition where the strcpy function is used to copy user-supplied data into a fixed-size buffer of only 40 bytes. This primitive operation lacks proper bounds checking mechanisms, allowing an attacker to supply an arbitrarily long "user" field value that exceeds the allocated buffer space. The video-core process fails to validate the length of incoming JSON data before performing the string copy operation, creating a deterministic overflow condition that can be reliably exploited. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a direct violation of secure coding practices for input validation and memory management. The vulnerability's exploitation potential is amplified by the fact that it requires no authentication or privileged access, making it accessible via unauthenticated HTTP requests to the device's network interface.
The operational impact of CVE-2018-3863 extends beyond simple device compromise, as the SmartThings Hub serves as a central coordinator for numerous IoT devices within residential and commercial environments. An attacker who successfully exploits this vulnerability gains unauthorized access to the device's operating system, potentially enabling them to intercept communications between connected smart devices, modify device configurations, or establish persistent access points within the network. The attack surface is particularly dangerous in smart home environments where the hub controls lighting, security systems, temperature controls, and other critical infrastructure. The vulnerability could be leveraged for lateral movement within networks, especially when the hub is connected to corporate or residential networks with multiple IoT devices. This scenario aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where attackers could execute arbitrary commands on the compromised device. The vulnerability also enables potential data exfiltration from connected devices and could facilitate more sophisticated attacks such as man-in-the-middle operations against other IoT devices communicating through the compromised hub.
Mitigation strategies for CVE-2018-3863 should prioritize immediate firmware updates from Samsung, as the vendor has released patches addressing this specific vulnerability. Network administrators should implement strict firewall rules to limit access to the SmartThings Hub's HTTP interfaces, particularly blocking external access to the device unless absolutely necessary. The deployment of network segmentation can help contain potential compromise within specific zones, preventing lateral movement across connected IoT devices. Additional defensive measures include monitoring for unusual HTTP traffic patterns and implementing intrusion detection systems that can identify malformed JSON payloads attempting to exploit this specific buffer overflow condition. Security professionals should also consider disabling unnecessary services and features on the device, reducing the attack surface available to potential attackers. Organizations should conduct thorough inventory assessments to identify all affected SmartThings Hub devices and ensure proper patch management procedures are in place to prevent similar vulnerabilities from remaining unaddressed in the future. The vulnerability serves as a reminder of the critical importance of input validation and proper memory management in embedded systems, particularly those operating in home and enterprise IoT environments where security failures can have significant consequences.