CVE-2007-4995 in OpenSSL
Summary
by MITRE
Off-by-one error in the DTLS implementation in OpenSSL 0.9.8 before 0.9.8f allows remote attackers to execute arbitrary code via unspecified vectors.
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Analysis
by VulDB Data Team • 07/28/2019
The vulnerability identified as CVE-2007-4995 represents a critical off-by-one error within the Datagram Transport Layer Security implementation of OpenSSL versions prior to 0.9.8f. This flaw exists in the DTLS protocol handling mechanism where a boundary condition error occurs during packet processing, specifically affecting how the software manages buffer boundaries when processing incoming DTLS records. The vulnerability stems from improper validation of packet lengths and buffer limits, creating a scenario where an attacker can manipulate data structures to overwrite adjacent memory locations. This type of error falls under CWE-129, which encompasses improper validation of array index bounds, and specifically relates to CWE-125, which addresses out-of-bounds read conditions that can lead to arbitrary code execution. The issue is particularly dangerous because it affects the core cryptographic protocol implementation that secures internet communications, making it a prime target for exploitation by threat actors seeking to compromise secure communication channels.
The technical exploitation of this vulnerability occurs when an attacker sends specially crafted DTLS packets to a vulnerable OpenSSL server or client. The off-by-one error manifests during the packet parsing phase where the implementation incorrectly calculates buffer boundaries, allowing an attacker to inject data that overflows into adjacent memory regions. This overflow can overwrite critical program variables, return addresses, or function pointers, potentially enabling code execution. The attack vector is remote and does not require authentication, making it particularly dangerous in networked environments where DTLS is deployed. The vulnerability affects the handshake process and record processing within the DTLS implementation, creating opportunities for attackers to inject malicious payloads that can be executed in the context of the affected application. The exploitability of this vulnerability is enhanced by the fact that it operates at the protocol level, meaning that successful exploitation can compromise the entire secure communication stack.
The operational impact of CVE-2007-4995 extends beyond simple code execution to encompass complete system compromise when exploited successfully. Organizations using vulnerable OpenSSL implementations face significant risks including data breaches, man-in-the-middle attacks, and potential full system takeovers. The vulnerability affects a wide range of applications that rely on OpenSSL for secure communications, including web servers, email servers, and any application implementing DTLS for secure data transmission. Security professionals must understand that this vulnerability operates at the foundational level of secure communications, making it particularly dangerous in environments where cryptographic security is paramount. The attack can be executed without requiring specific user interaction or authentication, making it a preferred target for automated exploitation tools. Organizations should consider the broader implications of this vulnerability in their security posture, particularly in environments where DTLS is used for critical communications.
Mitigation strategies for CVE-2007-4995 primarily focus on immediate software updates and system hardening measures. The most effective solution involves upgrading to OpenSSL version 0.9.8f or later, which includes the necessary patches to address the off-by-one error in the DTLS implementation. System administrators should conduct comprehensive vulnerability assessments to identify all systems running vulnerable OpenSSL versions and prioritize remediation efforts accordingly. Network segmentation and access controls can provide additional defense-in-depth measures while patches are deployed. Monitoring for suspicious network traffic patterns and anomalous DTLS handshake behavior can help detect exploitation attempts. Security teams should implement intrusion detection systems that can identify potential exploitation attempts based on known attack signatures. The vulnerability also underscores the importance of maintaining up-to-date cryptographic libraries and implementing regular security audits to identify and remediate similar issues before they can be exploited. Organizations should consider implementing certificate pinning and other cryptographic best practices to reduce the attack surface. This vulnerability aligns with ATT&CK technique T1059, which covers command and control through execution of code, and T1566, which involves phishing attacks that can leverage such vulnerabilities to establish persistent access to systems.