CVE-2017-7654 in Mosquitto
Summary
by MITRE
In Eclipse Mosquitto 1.4.15 and earlier, a Memory Leak vulnerability was found within the Mosquitto Broker. Unauthenticated clients can send crafted CONNECT packets which could cause a denial of service in the Mosquitto Broker.
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Analysis
by VulDB Data Team • 03/21/2023
The Eclipse Mosquitto broker vulnerability identified as CVE-2017-7654 represents a critical memory leak issue affecting versions 1.4.15 and earlier. This vulnerability resides within the broker's handling of CONNECT packets from unauthenticated clients, creating a pathway for malicious actors to exploit the system's memory management mechanisms. The flaw specifically manifests when the broker processes malformed or crafted CONNECT packets that trigger improper memory allocation and subsequent failure to release allocated resources. This memory management failure occurs during the initial connection phase of the MQTT protocol implementation, where the broker fails to properly handle client authentication requests that lack proper credentials or contain malformed data structures.
The technical implementation of this vulnerability stems from insufficient input validation within the broker's authentication processing module. When unauthenticated clients send CONNECT packets with malformed protocol elements, the Mosquitto broker's internal memory allocation routines allocate resources to process these packets but fail to properly deallocate them upon encountering protocol violations or authentication failures. This creates a progressive memory consumption pattern that can rapidly exhaust available system resources. The vulnerability operates at the application layer and specifically targets the broker's protocol parsing and authentication handling components, making it particularly dangerous as it requires no prior authentication credentials to exploit. The flaw aligns with CWE-401, which categorizes memory leak vulnerabilities in software systems, and represents a classic example of resource exhaustion through improper memory management.
Operationally, this vulnerability enables a denial of service attack that can severely impact the availability of MQTT broker services. An attacker can repeatedly send crafted CONNECT packets to the vulnerable broker, causing progressive memory consumption that eventually leads to system instability or complete service disruption. The attack vector is particularly concerning because it requires no authentication, making it accessible to anyone who can reach the broker's network interface. The memory leak can accumulate over time, potentially causing the broker to crash or become unresponsive, thereby disrupting all MQTT-based communication services that depend on the affected system. Network monitoring tools would typically show increasing memory usage patterns that correlate with the attack, making detection possible through routine system administration practices.
The impact of this vulnerability extends beyond simple service disruption, as it can compromise the reliability of IoT ecosystems and industrial automation systems that rely on MQTT brokers for communication. Organizations using vulnerable Mosquitto versions may experience cascading failures in their connected systems, particularly in environments where broker availability is critical for operational continuity. The vulnerability affects systems ranging from smart home installations to industrial control systems where MQTT brokers serve as communication hubs. Mitigation strategies include immediate patching to versions 1.4.16 and later, which contain the necessary memory management fixes. Network-level protections such as rate limiting for connection attempts and firewall rules to restrict unauthorized access to broker ports can provide temporary mitigation while patches are deployed. Additionally, implementing connection monitoring and memory usage alerts can help detect exploitation attempts and provide early warning of potential attacks. The vulnerability demonstrates the importance of proper resource management in network services and highlights the need for comprehensive input validation and memory safety practices in broker implementations. Organizations should also consider implementing intrusion detection systems that can identify unusual connection patterns and automated response mechanisms to limit the impact of such attacks.