CVE-2021-3152 in Home Assistant
Summary
by MITRE • 01/26/2021
** DISPUTED ** Home Assistant before 2021.1.3 does not have a protection layer that can help to prevent directory-traversal attacks against custom integrations. NOTE: the vendor's perspective is that the vulnerability itself is in custom integrations written by third parties, not in Home Assistant; however, Home Assistant does have a security update that is worthwhile in addressing this situation.
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Analysis
by VulDB Data Team • 08/03/2024
The vulnerability identified as CVE-2021-3152 affects Home Assistant versions prior to 2021.1.3 and represents a directory traversal security flaw that specifically impacts custom integrations within the platform. This issue arises from the absence of proper protection mechanisms that should prevent unauthorized file access attempts. The vulnerability is particularly concerning because it allows attackers to potentially access sensitive files and directories that should remain protected within the system's file structure. Security researchers have noted that while the vendor maintains that the core vulnerability lies within third-party custom integrations rather than the Home Assistant core itself, the platform's responsibility to address such security concerns remains valid. The disputed nature of this vulnerability stems from the vendor's perspective that custom integrations are the primary source of risk, yet the platform's security update demonstrates recognition of the broader implications for user environments.
The technical flaw manifests through inadequate input validation and sanitization mechanisms within Home Assistant's handling of file paths when processing custom integration requests. Directory traversal attacks exploit this weakness by manipulating file path references to access files outside of intended directories. When custom integrations make requests to the system's file handling components, the lack of proper path validation allows attackers to craft malicious requests that could traverse directories and access sensitive system files, configuration data, or user information. This vulnerability aligns with CWE-22, which specifically addresses directory traversal and path traversal issues in software applications. The flaw operates by bypassing normal access controls that should restrict file system access to authorized users and processes, potentially exposing critical system components to unauthorized access.
The operational impact of CVE-2021-3152 extends beyond simple file access violations to potentially compromise entire Home Assistant installations. Attackers could leverage this vulnerability to access configuration files that might contain authentication credentials, API keys, or other sensitive information. The implications are particularly severe in environments where Home Assistant serves as a central automation hub for smart home systems, as unauthorized access could provide attackers with control over connected devices and automated processes. This vulnerability could enable attackers to escalate privileges, access personal data, or even disrupt home automation services. The attack surface is amplified when considering that Home Assistant installations often run with elevated privileges and may be accessible from network interfaces, making the potential impact more significant than a simple file disclosure vulnerability.
Mitigation strategies for CVE-2021-3152 should focus on immediate implementation of the vendor-provided security update to version 2021.1.3 or later, which addresses the core directory traversal protection gaps. Organizations should also implement comprehensive monitoring of file access patterns and network traffic to detect potential exploitation attempts. Security teams should conduct thorough reviews of all custom integrations installed on affected systems, ensuring that third-party components follow secure coding practices and proper input validation. Network segmentation and access controls should be implemented to limit exposure of Home Assistant systems to untrusted networks. Additionally, regular security audits of the Home Assistant installation and its custom components are recommended to identify and remediate similar vulnerabilities. The remediation process should include updating the core platform, reviewing integration security configurations, and implementing proper file system access controls that align with the principle of least privilege. This vulnerability underscores the importance of maintaining up-to-date software components and the critical need for security-conscious development practices in home automation platforms. The ATT&CK framework classification for this vulnerability would align with techniques involving privilege escalation and credential access through directory traversal methods, making it a significant concern for defenders implementing security controls in home automation environments.