CVE-2018-3832 in Insteon
Summary
by MITRE
An exploitable firmware update vulnerability exists in Insteon Hub running firmware version 1013. The HTTP server allows for uploading arbitrary MPFS binaries that could be modified to enable access to hidden resources which allow for uploading unsigned firmware images to the device. To trigger this vulnerability, an attacker can upload an MPFS binary via the '/mpfsupload' HTTP form and later on upload the firmware via a POST request to 'firmware.htm'.
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Analysis
by VulDB Data Team • 05/04/2023
The vulnerability described in CVE-2018-3832 represents a critical security flaw in Insteon Hub firmware that enables unauthorized firmware updates through a combination of improper access controls and insecure file upload mechanisms. This vulnerability exists within the device's HTTP server implementation and specifically targets the firmware update process that occurs in firmware version 1013. The flaw stems from insufficient validation of uploaded files and lack of proper authentication checks during the firmware update workflow, creating a pathway for attackers to bypass normal security controls and gain unauthorized access to the device's firmware update capabilities.
The technical exploitation of this vulnerability follows a multi-stage attack pattern that begins with the upload of a malicious MPFS binary through the '/mpfsupload' HTTP endpoint. This initial upload allows attackers to modify the device's filesystem and gain access to hidden resources that are typically restricted to authorized users only. The vulnerability is particularly concerning because it leverages the legitimate firmware update infrastructure to execute malicious code, making it difficult to detect through standard network monitoring. The MPFS binary upload mechanism fails to properly validate file types, content, or integrity checks, allowing attackers to inject modified firmware images that can potentially execute arbitrary code with elevated privileges on the device.
The operational impact of this vulnerability extends beyond simple unauthorized access to include complete device compromise and potential network infiltration. Once an attacker successfully uploads and executes malicious firmware, they can gain persistent access to the Insteon Hub, potentially using it as a pivot point to attack other devices on the same network. The vulnerability affects the device's core security model by allowing attackers to bypass the normal firmware verification processes that are designed to prevent unauthorized firmware installations. This creates a persistent threat vector that can remain active even after device reboots, as the malicious firmware modifications persist in the device's memory. The vulnerability also undermines the device's ability to maintain secure communications with other networked devices, as the compromised hub can be used to intercept or manipulate network traffic.
Mitigation strategies for this vulnerability should focus on implementing proper access controls and authentication mechanisms for all firmware update processes. Network segmentation and firewall rules should be configured to restrict access to the affected HTTP endpoints to trusted network segments only, while also implementing strict file validation and integrity checks for all uploaded files. Device administrators should regularly update firmware to versions that address this vulnerability, and organizations should implement network monitoring to detect unusual file upload patterns or access to hidden resources. The vulnerability aligns with CWE-434 which describes insecure file upload vulnerabilities, and represents a significant risk under ATT&CK technique T1059 for execution through malicious firmware modifications. Additionally, the vulnerability demonstrates characteristics of privilege escalation and persistence mechanisms that align with ATT&CK techniques for maintaining access and executing malicious code within networked environments. Organizations should also consider implementing network-based intrusion detection systems to monitor for exploitation attempts targeting the specific HTTP endpoints mentioned in the vulnerability description.