CVE-2017-7243 in tinydtls
Summary
by MITRE
Eclipse tinydtls 0.8.2 for Eclipse IoT allows remote attackers to cause a denial of service (DTLS peer crash) by sending a "Change cipher spec" packet without pre-handshake.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/14/2020
The vulnerability identified as CVE-2017-7243 affects Eclipse tinydtls version 0.8.2 within the Eclipse IoT ecosystem, presenting a significant denial of service risk that can be exploited by remote attackers. This flaw specifically targets the DTLS (Datagram Transport Layer Security) implementation and occurs when a malicious actor sends a "Change cipher spec" packet without completing the necessary pre-handshake procedures. The issue stems from inadequate validation of the DTLS handshake sequence, where the protocol fails to properly handle unexpected packet ordering or missing handshake components that should precede the change cipher spec message.
The technical flaw manifests in the DTLS peer implementation where the system does not perform proper state validation before processing the change cipher spec packet. When such a packet arrives without the required pre-handshake elements, the tinydtls library crashes or becomes unstable, resulting in a complete denial of service condition for the affected DTLS peer. This vulnerability is particularly concerning because it operates at the protocol level and can be triggered remotely without requiring authentication or prior access to the system. The flaw represents a classic example of improper input validation and state management in cryptographic protocol implementations, which aligns with CWE-248, or "Uncaught Exception," and CWE-362, "Concurrent Execution using Shared Resource with Improper Synchronization."
From an operational impact perspective, this vulnerability exposes IoT devices and systems that rely on Eclipse tinydtls to potential disruption attacks that can render them completely inoperable. The denial of service can affect any device or service that implements DTLS for secure communication, including smart home devices, industrial sensors, and embedded systems. Attackers can exploit this weakness to continuously crash DTLS peers, making the affected systems unavailable for legitimate communication. The impact extends beyond simple service disruption as it can compromise the integrity of IoT networks where multiple devices rely on secure DTLS connections for proper operation. This vulnerability particularly affects environments where device availability and reliability are critical, such as industrial control systems, smart grid infrastructure, and healthcare IoT deployments.
The exploitation of CVE-2017-7243 aligns with several ATT&CK framework techniques including T1499.004, "Endpoint Denial of Service," and T1566.001, "Phishing," as attackers may use this vulnerability as part of broader attack campaigns. Organizations should implement immediate mitigations including updating to patched versions of Eclipse tinydtls, implementing network segmentation to limit exposure, and deploying intrusion detection systems that can monitor for anomalous DTLS handshake patterns. The vulnerability also highlights the importance of proper error handling in cryptographic libraries and underscores the need for comprehensive protocol testing that includes edge cases and unexpected packet sequences. Security monitoring should focus on identifying unusual DTLS peer behavior and implementing automatic recovery mechanisms to minimize the impact of successful exploitation attempts.