CVE-2018-3876 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 64 bytes. An attacker can send an arbitrarily long "bucket" value in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 05/17/2023
The vulnerability described in CVE-2018-3876 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 functionality, which processes authentication-related data submitted to the device's web interface. The flaw manifests when the system processes user-supplied input through the "bucket" parameter, creating a dangerous condition where input validation is completely absent. The vulnerability stems from the improper use of the strncpy function, which despite its name suggesting safe copying, fails to null-terminate the destination buffer when the source string exceeds the specified limit. This particular implementation flaw allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution or system compromise.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-121, which describes stack-based buffer overflow conditions. The destination buffer size of exactly 64 bytes creates a predictable attack surface where an attacker can craft malicious input that exceeds this boundary. When the strncpy function processes a "bucket" value longer than 64 bytes, it copies the specified number of bytes but does not guarantee null termination, leaving the buffer in an undefined state. This condition creates memory corruption that can be leveraged by attackers to overwrite return addresses, function pointers, or other critical program state information. The specific nature of the HTTP server implementation suggests this vulnerability could be exploited through web-based attacks, potentially allowing remote code execution without authentication. The attack vector is particularly concerning because it requires no prior authentication and can be executed through standard HTTP requests.
From an operational perspective, this vulnerability presents significant risk to users of Samsung SmartThings Hub devices, particularly in environments where these hubs serve as central control points for home automation systems. The exploitation of this flaw could result in complete system compromise, allowing attackers to gain unauthorized access to the device's network, potentially enabling them to control connected IoT devices, access personal data, or use the compromised hub as a pivot point for attacking other devices on the network. The vulnerability's impact extends beyond simple device compromise, as SmartThings hubs often integrate with numerous other smart home devices, creating a potential attack surface that could escalate to broader network infiltration. Organizations and individuals relying on these devices for security or automation purposes face substantial risk, as the vulnerability could be exploited to gain persistent access to their smart home environments. The lack of input validation and the predictable buffer size make this vulnerability particularly attractive to automated exploitation tools, increasing the likelihood of widespread compromise.
Mitigation strategies for this vulnerability should include immediate firmware updates from Samsung, as the company would have likely released patches addressing this specific buffer overflow condition. Network segmentation and access control measures can help reduce the potential impact by limiting access to the SmartThings hub to trusted networks and devices. Implementing web application firewalls or intrusion prevention systems that can detect and block malformed HTTP requests containing overly long "bucket" parameters provides an additional layer of defense. Security monitoring should include detection of unusual HTTP traffic patterns that might indicate exploitation attempts, particularly focusing on requests with parameter values exceeding normal operational bounds. The vulnerability also highlights the importance of proper input validation and secure coding practices, particularly around buffer handling functions, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution through web interfaces. Organizations should also consider implementing network-based intrusion detection systems that can identify and alert on patterns consistent with buffer overflow exploitation attempts, ensuring that such vulnerabilities are detected and mitigated before they can be effectively exploited in the wild.