CVE-2018-3903 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. The memcpy call overflows the destination buffer, which has a size of 512 bytes. An attacker can send an arbitrarily long "url" value in order to overwrite the saved-PC with 0x42424242.
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Analysis
by VulDB Data Team • 05/04/2023
The vulnerability identified as CVE-2018-3903 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 enables remote code execution. This issue stems from improper input validation within the JSON payload processing mechanism, where the system fails to adequately sanitize user-controlled data before copying it into a fixed-size buffer. The vulnerability manifests through an HTTP request that triggers the problematic memcpy operation, making it accessible to remote attackers without requiring physical access or authentication credentials.
The technical implementation of this flaw involves a stack-based buffer overflow where the destination buffer is allocated with a fixed size of 512 bytes, yet the memcpy function does not perform bounds checking before copying data from the user-controlled "url" field in the JSON payload. This allows an attacker to craft a malicious HTTP request containing an arbitrarily long "url" value that exceeds the buffer capacity, resulting in the overwrite of adjacent stack memory locations. The specific overwrite of the saved program counter with the value 0x42424242 demonstrates that the attacker can control the instruction pointer, potentially enabling arbitrary code execution or system compromise.
From an operational security perspective, this vulnerability presents a severe risk to home and enterprise IoT deployments, as it allows remote attackers to gain unauthorized control over the SmartThings hub device. The attack vector requires only a simple HTTP request, making it easily exploitable through web-based attack frameworks. The impact extends beyond local device compromise to potentially enable attackers to access other networked devices within the same ecosystem, as the SmartThings hub typically serves as a central coordinator for various smart home devices. The vulnerability affects the device's core functionality and could lead to complete system takeover, data exfiltration, or use as a pivot point for further network infiltration.
Mitigation strategies should focus on immediate firmware updates from Samsung to address the buffer overflow condition through proper bounds checking and input validation. Network segmentation and firewall rules can help limit exposure by restricting HTTP access to the affected device, while monitoring solutions should be implemented to detect anomalous HTTP traffic patterns. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is categorized under the broader category of CWE-787 Out-of-bounds Write, and represents a technique commonly used in the ATT&CK framework under T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution. Organizations should also consider implementing intrusion detection systems specifically tuned to detect the signature patterns associated with this exploit, and establish incident response procedures to handle potential compromise scenarios.