CVE-2017-9868 in Mosquitto
Summary
by MITRE
In Mosquitto through 1.4.12, mosquitto.db (aka the persistence file) is world readable, which allows local users to obtain sensitive MQTT topic information.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability identified as CVE-2017-9868 affects the Mosquitto MQTT broker software version 1.4.12 and earlier, representing a critical security flaw in the persistence mechanism that stores MQTT message data. This issue stems from improper file permissions where the mosquitto.db file, which serves as the primary persistence database for MQTT broker operations, is created with world-readable permissions. The vulnerability exists within the broker's configuration and file system handling processes that fail to enforce proper access controls on sensitive data storage files.
The technical flaw manifests when the Mosquitto broker initializes and creates its persistence database file without setting appropriate file permissions. This allows any local user on the system to read the mosquitto.db file directly, bypassing the normal access control mechanisms that should protect sensitive MQTT topic information. The database contains all published messages and topic subscriptions that the broker has stored for persistence purposes, making it a valuable target for information disclosure attacks. This vulnerability is classified under CWE-732 as an Incorrect Permission Assignment for Critical Resource, which specifically addresses situations where critical system resources are granted inappropriate access permissions.
The operational impact of this vulnerability is significant for organizations relying on Mosquitto for MQTT communications, as it enables local privilege escalation and information disclosure attacks. An attacker with local access to the system can extract all stored MQTT messages, topic names, and potentially sensitive data that was published through the broker. This compromises the confidentiality of communications that were intended to be secure within the MQTT ecosystem, particularly affecting industrial IoT deployments, smart home systems, and enterprise messaging infrastructures where MQTT brokers are commonly deployed. The vulnerability affects the principle of least privilege and can lead to exposure of proprietary information, operational details, or sensitive data flows within the organization's network infrastructure.
Mitigation strategies for CVE-2017-9868 should focus on immediate permission fixes and configuration updates to prevent unauthorized access to the persistence database. System administrators should ensure that the mosquitto.db file is created with restrictive permissions, typically limiting access to the user account running the Mosquitto service. The recommended approach includes setting file permissions to 600 or 640, ensuring that only the broker process and authorized administrators can access the database. Additionally, organizations should update to Mosquitto version 1.4.13 or later, which includes fixes for this permission issue. Security monitoring should be implemented to detect unauthorized access attempts to persistence files, and regular security audits should verify that proper file permissions are maintained across all broker instances. This vulnerability also aligns with ATT&CK technique T1005 for Data from Local System, where adversaries attempt to access sensitive data stored locally on compromised systems. Organizations should also consider implementing mandatory access controls and regular permission reviews as part of their security posture to prevent similar issues in other services that maintain persistent data stores.