CVE-2016-2179 in Business Intelligence Enterprise Edition
Summary
by MITRE
The DTLS implementation in OpenSSL before 1.1.0 does not properly restrict the lifetime of queue entries associated with unused out-of-order messages, which allows remote attackers to cause a denial of service (memory consumption) by maintaining many crafted DTLS sessions simultaneously, related to d1_lib.c, statem_dtls.c, statem_lib.c, and statem_srvr.c.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2016-2179 represents a critical memory exhaustion flaw within OpenSSL's Datagram Transport Layer Security implementation that affects versions prior to 1.1.0. This weakness specifically targets the DTLS protocol handling mechanisms where the software fails to adequately manage memory resources when processing out-of-order messages during DTLS session establishment. The issue stems from improper lifetime management of queue entries that store information about unused messages received out of sequence, creating a persistent memory leak scenario that can be exploited by remote attackers.
The technical root cause of this vulnerability lies in the insufficient garbage collection and memory cleanup procedures within the DTLS state machine components. When OpenSSL processes DTLS sessions, it maintains queues to store messages that arrive out of order, allowing for proper reassembly and processing. However, the implementation fails to properly terminate or remove these queue entries once they are no longer needed or when sessions are abandoned, leading to continuous memory accumulation. The affected files d1_lib.c, statem_dtls.c, statem_lib.c, and statem_srvr.c contain the specific logic where this memory management failure occurs, particularly during the state transition handling and session management phases of DTLS communication.
This vulnerability creates a significant operational impact by enabling remote attackers to perform sustained denial of service attacks against systems running vulnerable OpenSSL versions. Attackers can maintain numerous crafted DTLS sessions simultaneously, each consuming memory resources through the accumulation of unused message queue entries. The memory consumption grows linearly with the number of active sessions, potentially exhausting available system memory and causing legitimate service requests to fail. This type of attack is particularly dangerous in high-traffic environments where the system's memory resources are already constrained, as it can effectively render the service unavailable to legitimate users.
The attack vector for CVE-2016-2179 operates through the DTLS protocol's session establishment and message processing mechanisms, where an attacker can create multiple concurrent DTLS connections with malformed or crafted messages designed to trigger the memory leak behavior. The vulnerability aligns with CWE-400, which categorizes improper resource cleanup or release as a common weakness leading to resource exhaustion attacks. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to Network Denial of Service, where adversaries leverage protocol implementation flaws to consume system resources and disrupt service availability. The mitigation strategy involves upgrading to OpenSSL 1.1.0 or later versions where the memory management has been corrected to properly terminate unused queue entries, alongside implementing network-level protections such as connection rate limiting and monitoring for unusual memory consumption patterns.
This vulnerability demonstrates the critical importance of proper resource management in cryptographic protocol implementations, as memory leaks in security libraries can have severe operational consequences. The flaw exemplifies how seemingly minor implementation details in state machine handling can create significant security risks, particularly in protocols like DTLS that require sophisticated session management and message ordering. Organizations should prioritize immediate patching of affected systems and implement monitoring solutions to detect potential exploitation attempts, as the vulnerability can be exploited without requiring authentication or special privileges. The issue also highlights the need for comprehensive testing of protocol implementations under stress conditions to identify resource management flaws that could be exploited in real-world scenarios.