CVE-2018-18764 in Mongoose
Summary
by MITRE
An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13. It is a heap-based buffer over-read in a parse_mqtt getu16 call. A specially crafted MQTT SUBSCRIBE packet can cause an arbitrary out-of-bounds memory read potentially resulting in information disclosure and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.
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Analysis
by VulDB Data Team • 04/07/2020
The vulnerability CVE-2018-18764 represents a critical heap-based buffer over-read flaw within the MQTT packet parsing implementation of Cesanta Mongoose version 6.13. This issue resides in the parse_mqtt function's getu16 call mechanism, which processes MQTT protocol messages containing subscription requests. The vulnerability manifests when the software attempts to read data from memory locations beyond the allocated buffer boundaries during the parsing of MQTT SUBSCRIBE packets. Such arbitrary memory read operations can potentially expose sensitive information stored in adjacent memory regions, including authentication credentials, session data, or system configuration details. The flaw demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read vulnerabilities, and aligns with ATT&CK technique T1005 for data from local system, as attackers could leverage this vulnerability to extract confidential information from the target system.
The technical exploitation of this vulnerability requires an attacker to craft a malicious MQTT SUBSCRIBE packet that triggers the flawed parsing logic within the Mongoose library. When the vulnerable software processes this specially constructed packet, the getu16 function attempts to read two bytes from memory locations that extend beyond the intended buffer boundaries. This out-of-bounds memory access can result in unpredictable behavior, including information disclosure through memory content exposure, or complete denial of service when the application crashes due to accessing invalid memory addresses. The heap-based nature of the vulnerability indicates that the memory corruption occurs within dynamically allocated memory regions, making the exploitation more complex but also more potentially damaging. The vulnerability affects systems that utilize Cesanta Mongoose for MQTT protocol handling, particularly those implementing MQTT brokers or clients that process subscription requests from untrusted network sources.
The operational impact of CVE-2018-18764 extends beyond simple information disclosure, as it can severely compromise system availability through denial of service attacks. Network-based attackers can exploit this vulnerability without requiring authentication or physical access to the target system, making it particularly dangerous in IoT environments where MQTT protocol is commonly used for device communication. The vulnerability affects a wide range of applications including smart home systems, industrial control networks, and IoT device management platforms that rely on Mongoose for MQTT protocol support. Organizations using affected versions of Cesanta Mongoose should consider the potential for cascading effects, as information disclosure could lead to further exploitation opportunities, while denial of service attacks could disrupt critical infrastructure operations. The vulnerability's network accessibility means that attackers can potentially exploit it from anywhere on the internet, particularly targeting publicly exposed MQTT services or devices that communicate over MQTT protocols.
Mitigation strategies for CVE-2018-18764 should prioritize immediate patching of affected Cesanta Mongoose installations to version 6.14 or later, which contains the necessary fixes for the heap-based buffer over-read vulnerability. Organizations should implement network segmentation and access controls to limit exposure of MQTT services to trusted networks only, reducing the attack surface for potential exploitation attempts. Monitoring network traffic for suspicious MQTT SUBSCRIBE packets and implementing intrusion detection systems can help identify exploitation attempts before they succeed. Additionally, deploying application-level firewalls or proxies that validate MQTT packet structures before forwarding them to vulnerable applications can provide an additional layer of defense. Security teams should also consider implementing memory protection mechanisms such as address space layout randomization and stack canaries to make exploitation more difficult. Regular vulnerability assessments and penetration testing should be conducted to identify other potential MQTT protocol implementations that may be affected by similar buffer over-read vulnerabilities, ensuring comprehensive protection against related threats in the MQTT ecosystem.