CVE-2009-1377 in OpenSSL
Summary
by MITRE
The dtls1_buffer_record function in ssl/d1_pkt.c in OpenSSL 0.9.8k and earlier 0.9.8 versions allows remote attackers to cause a denial of service (memory consumption) via a large series of "future epoch" DTLS records that are buffered in a queue, aka "DTLS record buffer limitation bug."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/04/2019
The vulnerability described in CVE-2009-1377 represents a critical denial of service flaw within the OpenSSL implementation of the Datagram Transport Layer Security protocol. This issue affects OpenSSL versions 0.9.8k and earlier, specifically targeting the dtls1_buffer_record function located in the ssl/d1_pkt.c source file. The flaw manifests when remote attackers exploit a weakness in the DTLS record buffering mechanism by sending a continuous stream of "future epoch" DTLS records that accumulate in an internal queue structure.
The technical nature of this vulnerability stems from inadequate bounds checking and resource management within the DTLS protocol implementation. When DTLS records arrive with future epoch numbers that cannot be immediately processed, the system buffers these records in anticipation of future processing. However, the implementation lacks proper limitations on the number of such buffered records, allowing attackers to continuously submit future epoch records that accumulate indefinitely in memory. This creates a memory exhaustion condition where the queue grows without bounds, consuming available system resources and ultimately leading to service unavailability.
From an operational perspective, this vulnerability presents a significant risk to any system utilizing OpenSSL 0.9.8k or earlier versions for DTLS communications. The attack requires minimal resources from the attacker, who only needs to establish a DTLS connection and begin sending appropriately crafted future epoch records. The impact is severe as it can completely consume system memory resources, causing the targeted service to become unresponsive or crash entirely. This vulnerability directly maps to CWE-400, which addresses "Uncontrolled Resource Consumption" and specifically relates to the improper handling of resource allocation in network protocols.
The attack pattern aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to resource exhaustion and denial of service operations. The vulnerability can be exploited through network-based attacks that do not require authentication, making it particularly dangerous in environments where DTLS services are exposed to untrusted networks. The memory consumption aspect of this flaw also relates to ATT&CK technique T1499, which covers "Endpoint Denial of Service" through resource exhaustion attacks.
Mitigation strategies for CVE-2009-1377 primarily involve upgrading to OpenSSL versions 0.9.8l or later, where the buffering limitations have been properly implemented. Organizations should also consider implementing network-level protections such as rate limiting and connection tracking to prevent excessive buffering of DTLS records. Additionally, monitoring systems should be configured to detect unusual memory consumption patterns that might indicate exploitation attempts. The fix implemented in later versions typically includes enforcing maximum queue sizes and implementing proper timeout mechanisms for buffered records, preventing the accumulation of future epoch records that could lead to memory exhaustion.