CVE-2014-3466 in GnuTLS
Summary
by MITRE
Buffer overflow in the read_server_hello function in lib/gnutls_handshake.c in GnuTLS before 3.1.25, 3.2.x before 3.2.15, and 3.3.x before 3.3.4 allows remote servers to cause a denial of service (memory corruption) or possibly execute arbitrary code via a long session id in a ServerHello message.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2014-3466 represents a critical buffer overflow flaw within the GnuTLS cryptographic library implementation. This issue resides in the read_server_hello function located in lib/gnutls_handshake.c, affecting multiple versions of the library including those before 3.1.25, 3.2.x before 3.2.15, and 3.3.x before 3.3.4. The flaw manifests when remote servers send maliciously crafted ServerHello messages containing excessively long session identifiers, creating a scenario where memory corruption can occur during the SSL/TLS handshake process. This vulnerability operates at the protocol level and specifically targets the handshake mechanism that establishes secure connections between clients and servers.
The technical implementation of this buffer overflow stems from inadequate input validation within the read_server_hello function which fails to properly bounds-check the length of session identifiers received from server responses. When a malicious server sends a ServerHello message with an oversized session id field, the function attempts to copy this data into a fixed-size buffer without proper size verification. This classic buffer overflow condition allows an attacker to overwrite adjacent memory locations, potentially leading to unpredictable behavior including application crashes, memory corruption, or in severe cases, arbitrary code execution. The vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and can be categorized under ATT&CK technique T1059.007 for command and scripting interpreter execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it presents a potential path for remote code execution when exploited successfully. Any application or system utilizing GnuTLS versions affected by this flaw becomes susceptible to attacks during the SSL/TLS handshake phase, particularly when clients connect to untrusted or compromised servers. The memory corruption effects can cause applications to crash or behave unpredictably, while the potential for arbitrary code execution makes this vulnerability particularly dangerous in environments where GnuTLS is used for critical security operations. Network services, web browsers, email clients, and any software that relies on GnuTLS for secure communications are at risk. The vulnerability demonstrates how seemingly minor protocol implementation flaws can have significant security implications, especially when they occur during the initial connection establishment phase where proper authentication and encryption are crucial.
Mitigation strategies for CVE-2014-3466 primarily involve immediate patching of affected GnuTLS versions to the corrected releases. System administrators should prioritize updating all installations to versions 3.1.25, 3.2.15, or 3.3.4 respectively, depending on their current version. Additionally, network administrators can implement defensive measures such as monitoring for unusual ServerHello messages and implementing proper input validation at network boundaries. Organizations should also consider deploying intrusion detection systems that can identify malformed SSL/TLS handshakes. The vulnerability highlights the importance of proper bounds checking in cryptographic implementations and reinforces the need for regular security updates and vulnerability assessments. Given the potential for remote code execution, immediate remediation is essential, and organizations should conduct thorough inventory checks to identify all systems using vulnerable GnuTLS versions. This case study exemplifies how protocol-level vulnerabilities in security libraries can create widespread exposure across numerous applications and systems that depend on these foundational components for secure communications.