CVE-2014-0195 in Mac OS X
Summary
by MITRE
The dtls1_reassemble_fragment function in d1_both.c in OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h does not properly validate fragment lengths in DTLS ClientHello messages, which allows remote attackers to execute arbitrary code or cause a denial of service (buffer overflow and application crash) via a long non-initial fragment.
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Analysis
by VulDB Data Team • 02/20/2022
The vulnerability identified as CVE-2014-0195 represents a critical buffer overflow flaw within the OpenSSL implementation of the Datagram Transport Layer Security protocol. This weakness exists in the dtls1_reassemble_fragment function located in the d1_both.c source file, affecting multiple OpenSSL versions including 0.9.8 series before 0.9.8za, 1.0.0 series before 1.0.0m, and 1.0.1 series before 1.0.1h. The flaw specifically targets the handling of DTLS ClientHello messages where the system fails to properly validate fragment lengths during the reassembly process, creating a pathway for malicious actors to exploit the vulnerability through carefully crafted network packets.
The technical exploitation of this vulnerability occurs when an attacker sends a specially crafted DTLS ClientHello message containing a long non-initial fragment that exceeds the expected buffer boundaries. During the reassembly process, the function does not adequately validate the length of these fragments before copying them into memory buffers, leading to a classic buffer overflow condition. This overflow can result in memory corruption that allows remote attackers to execute arbitrary code on the vulnerable system or cause a denial of service through application crashes. The vulnerability manifests as a heap-based buffer overflow due to improper bounds checking in the fragment reassembly logic, which is classified under CWE-121 in the Common Weakness Enumeration catalog.
From an operational perspective, this vulnerability poses significant risk to any system utilizing OpenSSL for DTLS communications, particularly those in network infrastructure, web servers, and applications that rely on secure datagram communications. The attack surface is broad as DTLS is commonly used in VoIP systems, IoT devices, and any application requiring secure communication over unreliable networks. The vulnerability's impact ranges from complete system compromise when exploited for code execution to widespread service disruption through denial of service attacks, making it particularly dangerous in environments where availability is critical. Network-based attacks can be executed remotely without requiring authentication, and the exploit can be automated, potentially leading to large-scale disruptions across multiple systems simultaneously.
The mitigation strategies for CVE-2014-0195 primarily focus on immediate software updates to patched OpenSSL versions that address the fragment validation issue. Organizations should prioritize upgrading to OpenSSL 0.9.8za, 1.0.0m, or 1.0.1h and later versions where the buffer overflow has been corrected through proper input validation and bounds checking. Additional protective measures include implementing network segmentation and access controls to limit exposure, deploying intrusion detection systems that can identify suspicious DTLS traffic patterns, and monitoring for unusual connection behavior that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1210 for exploitation of remote services and T1499 for network disruption, making it a significant concern for security operations centers monitoring for advanced persistent threats. Organizations should also consider implementing rate limiting and connection throttling mechanisms to reduce the effectiveness of denial of service attacks targeting this vulnerability.