CVE-2017-7651 in Mosquitto
Summary
by MITRE
In Eclipse Mosquitto 1.4.14, a user can shutdown the Mosquitto server simply by filling the RAM memory with a lot of connections with large payload. This can be done without authentications if occur in connection phase of MQTT protocol.
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Analysis
by VulDB Data Team • 03/07/2023
The vulnerability identified as CVE-2017-7651 affects Eclipse Mosquitto version 1.4.14 and represents a critical resource exhaustion flaw that enables unauthorized users to disrupt server operations through memory manipulation. This vulnerability specifically targets the MQTT protocol connection phase, where malicious actors can exploit the server's handling of incoming connections and payload data to consume excessive system resources. The flaw allows an attacker to initiate multiple simultaneous connections and transmit large payloads, effectively causing the server to consume all available RAM memory. This type of denial of service attack leverages the server's lack of proper resource limiting mechanisms during the initial connection establishment process, making it particularly dangerous as it requires no authentication credentials to exploit.
The technical implementation of this vulnerability stems from insufficient input validation and resource management within the Mosquitto server's connection handling logic. During the MQTT protocol connection phase, the server does not adequately monitor or limit the number of concurrent connections or the size of payload data that can be transmitted during connection establishment. This creates a scenario where an attacker can flood the server with numerous connections, each carrying substantial payload data, leading to rapid memory exhaustion. The vulnerability manifests as a memory leak pattern where each connection consumes significant RAM resources without proper cleanup or resource allocation limits, ultimately causing the server to become unresponsive or crash entirely.
From an operational perspective, this vulnerability presents a severe threat to IoT deployments and messaging infrastructure that rely on Mosquitto as their MQTT broker. Organizations using this software in production environments face the risk of complete service disruption, potentially affecting critical operations that depend on message queuing and delivery. The impact extends beyond simple service interruption as the memory exhaustion can cause cascading failures in dependent systems, particularly in edge computing scenarios where server resources are limited. The vulnerability's accessibility, requiring no authentication for exploitation, makes it especially dangerous for publicly accessible MQTT brokers or those with open connection ports. This flaw directly aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" and represents a classic example of how inadequate resource management can lead to system compromise.
The mitigation strategies for CVE-2017-7651 should focus on implementing comprehensive resource limiting mechanisms and connection management policies. System administrators should configure connection limits, payload size restrictions, and connection rate limiting to prevent memory exhaustion attacks. The recommended approach includes setting maximum connection limits, implementing proper connection timeout mechanisms, and configuring appropriate memory allocation parameters within the Mosquitto configuration files. Additionally, network-level protections such as firewall rules and rate limiting at the network boundary can provide additional defense in depth. Organizations should also consider upgrading to patched versions of Mosquitto where this vulnerability has been addressed, as the maintainers have implemented proper resource management controls to prevent excessive memory consumption during connection establishment. This vulnerability demonstrates the importance of implementing proper resource management practices as outlined in ATT&CK technique T1499, which covers resource exhaustion attacks targeting system availability.