CVE-2014-8176 in OpenSSL
Summary
by MITRE
The dtls1_clear_queues function in ssl/d1_lib.c in OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h frees data structures without considering that application data can arrive between a ChangeCipherSpec message and a Finished message, which allows remote DTLS peers to cause a denial of service (memory corruption and application crash) or possibly have unspecified other impact via unexpected application data.
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Analysis
by VulDB Data Team • 05/21/2022
The vulnerability identified as CVE-2014-8176 represents a critical flaw in OpenSSL's DTLS implementation that specifically affects the dtls1_clear_queues function within ssl/d1_lib.c. This issue manifests in multiple OpenSSL versions including 0.9.8za and earlier, 1.0.0m and earlier, and 1.0.1h and earlier, creating a significant security risk for systems relying on DTLS protocol for secure communications. The flaw stems from improper handling of data structure cleanup during the DTLS handshake process, where the function fails to account for the possibility of application data arriving between critical handshake messages.
The technical root cause of this vulnerability lies in the improper synchronization between the DTLS handshake state machine and the processing of application data. During the DTLS handshake, when a ChangeCipherSpec message is received followed by a Finished message, the dtls1_clear_queues function prematurely frees certain data structures without considering that additional application data might arrive during this transitional period. This creates a race condition where memory management operations occur concurrently with data processing, leading to potential memory corruption scenarios.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks against DTLS-enabled services by sending carefully crafted application data packets between the ChangeCipherSpec and Finished messages. The impact extends beyond simple service disruption, as the memory corruption can potentially lead to application crashes or in some cases, more severe unspecified consequences that could compromise system stability. This vulnerability particularly affects services using DTLS for secure communication such as VoIP systems, IoT devices, and any network infrastructure relying on DTLS for encrypted data transmission.
The vulnerability maps to CWE-476 which describes NULL pointer dereference conditions, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. Organizations utilizing affected OpenSSL versions face significant risk as attackers can exploit this weakness to disrupt services without requiring authentication or specialized privileges. The attack vector is particularly concerning because it can be executed remotely against any DTLS server or client that has not been patched, making it a widespread threat across various network infrastructures.
Mitigation strategies should focus on immediate patching of all affected OpenSSL versions to the latest stable releases containing the fix. System administrators must also implement network-level monitoring to detect unusual application data patterns between handshake messages, and consider implementing rate limiting or connection validation mechanisms to reduce the attack surface. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems running affected OpenSSL versions and ensure proper patch management procedures are in place to prevent future exposure to similar vulnerabilities.