CVE-2009-1386 in OpenSSL
Summary
by MITRE
ssl/s3_pkt.c in OpenSSL before 0.9.8i allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a DTLS ChangeCipherSpec packet that occurs before ClientHello.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability described in CVE-2009-1386 represents a critical denial of service weakness within the OpenSSL implementation that affects versions prior to 0.9.8i. This flaw specifically resides in the ssl/s3_pkt.c file and manifests when processing DTLS ChangeCipherSpec packets that are received before the initial ClientHello message. The timing of this packet sequence creates a condition where the OpenSSL daemon becomes vulnerable to a NULL pointer dereference, ultimately leading to a complete crash of the affected service. The attack vector is particularly concerning because it can be exploited remotely without requiring authentication or prior access to the system, making it a significant threat to network availability.
The technical mechanism behind this vulnerability involves the improper handling of DTLS protocol state transitions within the OpenSSL library. When a ChangeCipherSpec message is received before the ClientHello handshake message, the internal state management fails to properly initialize required pointers, resulting in a NULL pointer dereference during packet processing. This condition violates standard protocol handling procedures and demonstrates a fundamental flaw in the state machine implementation for DTLS connections. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which represents a common class of programming errors that can lead to system instability and service disruption.
From an operational perspective, this vulnerability creates substantial risk for systems that rely on OpenSSL for secure communications, particularly those implementing DTLS protocols for applications such as VoIP, IoT devices, or any network services requiring secure datagram transport. The remote nature of the attack means that adversaries can exploit this weakness from anywhere on the network, potentially leading to widespread service disruption across multiple systems. The daemon crash resulting from this vulnerability can be particularly damaging in mission-critical environments where continuous availability is essential, as it may require manual intervention to restore service and could be exploited as part of larger attack campaigns targeting system availability.
The impact of this vulnerability extends beyond simple service disruption to encompass potential broader security implications within the attack lifecycle as defined by the MITRE ATT&CK framework. While primarily classified as a denial of service vector, such vulnerabilities can serve as precursors to more sophisticated attacks or be used to create distractions during other malicious activities. Organizations should consider this vulnerability as part of their broader threat landscape assessment, particularly when evaluating their defensive strategies against protocol-level attacks. The remediation approach involves updating to OpenSSL version 0.9.8i or later, which includes proper state validation and error handling for the specific DTLS packet sequence that triggers the vulnerability, ensuring that all affected systems receive timely patching to prevent exploitation.