CVE-2015-0206 in OpenSSL
Summary
by MITRE
Memory leak in the dtls1_buffer_record function in d1_pkt.c in OpenSSL 1.0.0 before 1.0.0p and 1.0.1 before 1.0.1k allows remote attackers to cause a denial of service (memory consumption) by sending many duplicate records for the next epoch, leading to failure of replay detection.
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Analysis
by VulDB Data Team • 03/01/2022
The vulnerability identified as CVE-2015-0206 represents a critical memory management flaw within the OpenSSL implementation that affects versions prior to 1.0.0p and 1.0.1k. This issue resides in the dtls1_buffer_record function located within the d1_pkt.c source file, which is responsible for handling DTLS (Datagram Transport Layer Security) packet processing. The flaw manifests when the system receives multiple duplicate records intended for the subsequent epoch, creating a scenario where the application fails to properly manage memory resources during replay detection operations. This memory leak directly impacts the system's ability to maintain stable operation under sustained attack conditions.
The technical execution of this vulnerability exploits the DTLS protocol's epoch management mechanism where records are processed in sequential epochs to maintain secure communication. When duplicate records arrive for the next epoch, the dtls1_buffer_record function fails to properly dispose of previously buffered records, leading to progressive memory accumulation. Each duplicate record triggers the buffering mechanism without proper cleanup, causing memory allocation to increase continuously until system resources are exhausted. This behavior creates a classic denial of service condition where legitimate system operations become impossible due to memory starvation, making the system unresponsive to valid requests.
From an operational perspective, this vulnerability presents a significant threat to systems relying on OpenSSL for DTLS implementations, particularly those handling high volumes of network traffic or serving critical services. The attack requires minimal resources from the attacker who only needs to send duplicate records, yet can cause substantial impact by consuming system memory at an accelerating rate. Network services such as VoIP systems, IoT devices, and any application utilizing DTLS for secure datagram communication become vulnerable to this attack vector. The vulnerability aligns with CWE-401, which specifically addresses improper management of memory allocation and deallocation, and represents a direct violation of secure coding practices for resource management in cryptographic libraries.
The attack pattern follows established patterns documented in the MITRE ATT&CK framework under the denial of service category, where adversaries leverage protocol implementation weaknesses to exhaust system resources. This vulnerability demonstrates how cryptographic libraries can be targeted for resource exhaustion attacks, particularly in environments where DTLS is used for secure communication. Organizations utilizing affected OpenSSL versions face potential service disruption and may experience cascading failures if the memory consumption leads to system instability. The impact extends beyond simple service interruption to potentially affect system availability and overall network infrastructure reliability.
Mitigation strategies for CVE-2015-0206 primarily focus on immediate software updates to patched OpenSSL versions, specifically upgrading to 1.0.0p or 1.0.1k and later releases. System administrators should implement monitoring solutions to detect unusual memory consumption patterns and establish automated alerting for memory usage thresholds. Network-level protections including rate limiting and duplicate record filtering can provide additional defense in depth. Organizations should also consider implementing memory allocation limits and process monitoring to prevent complete system exhaustion. The vulnerability highlights the importance of regular security patch management and continuous vulnerability assessment in cryptographic infrastructure to prevent exploitation of memory management flaws that can lead to critical service disruptions.