Horizon Alert
Summary of the vulnerability and why it matters
This advisory details a critical vulnerability in Home Assistant Core that could allow unauthenticated attackers to write arbitrary files to any directory on the host system. The exploit occurs during the initial setup process by uploading a crafted backup archive, manipulating a field to bypass security checks and gain unauthorized write access. The main concern is to confirm if this technology is in use and assess any potential exposure.
- Attackers write files anywhere on the system.
- Home Assistant is a central, networked smart home hub.
- Confirm use and assess potential exposure.
Attack Path
How an attacker could exploit the issue
An unauthenticated attacker can compromise a Home Assistant instance during its initial setup by uploading a specially crafted backup archive. This archive manipulates a file path within the backup, allowing the attacker to bypass the intended backup directory and write arbitrary files to any location on the host system. If the Home Assistant process has root privileges, this can lead to full control over the host.
- Unauthenticated network access required.
- Triggered by uploading a malicious backup archive.
- Enables arbitrary file write with root access.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow an unauthenticated attacker to write arbitrary files to any directory on the host filesystem. This is possible when the Home Assistant instance is undergoing initial onboarding and an attacker can upload a specially crafted backup archive. The attack manipulates a file within the archive to specify an absolute path, bypassing the intended backup directory and enabling the attacker to write content to any location on the filesystem, potentially leading to full system compromise if the process runs with root privileges.
- Host filesystem data and configuration.
- Crafted backup archive upload during onboarding.
- Arbitrary file write, potential system compromise.
Operational Fix
Recommended remediation, mitigation, and detection steps
The Home Assistant Core vulnerability impacts systems using the affected technology. Given its role as a network-accessible smart home hub, ownership likely falls to the platform or infrastructure team managing the Home Assistant deployment. The first practical step is to identify all instances of Home Assistant Core, assess their exposure and criticality, and confirm the accountable owner to plan remediation.
- Platform or infrastructure teams own the issue.
- Verify all Home Assistant Core instances.
- Plan risk-based remediation actions.
