CVE-2019-3829 in GnuTLS
Summary
by MITRE
A vulnerability was found in gnutls versions from 3.5.8 before 3.6.7. A memory corruption (double free) vulnerability in the certificate verification API. Any client or server application that verifies X.509 certificates with GnuTLS 3.5.8 or later is affected.
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Analysis
by VulDB Data Team • 08/17/2023
The vulnerability identified as CVE-2019-3829 represents a critical memory corruption issue within the GnuTLS cryptographic library that affects versions from 3.5.8 through 3.6.6. This flaw manifests as a double free vulnerability within the certificate verification API component of the library, creating a potential vector for remote code execution or denial of service attacks. The issue stems from improper memory management during the validation of X.509 certificates, where the library fails to correctly handle memory deallocation when processing certain certificate structures. This vulnerability impacts any application that relies on GnuTLS for secure communication and certificate validation, including web servers, email clients, and network security tools. The double free condition occurs when the same memory block is freed twice, which can lead to unpredictable behavior and potential exploitation by malicious actors. The vulnerability is particularly concerning because it affects the core certificate verification functionality that is fundamental to secure communications in countless applications and systems. The flaw exists in the certificate parsing and validation logic where the library does not properly track memory allocations and deallocations during the verification process. This type of memory corruption vulnerability is classified under CWE-415 as Double Free, which is a well-known category of memory safety issues that can be exploited to execute arbitrary code or cause system instability. The impact extends beyond individual applications to entire network infrastructures that depend on GnuTLS for secure communications, making this vulnerability particularly dangerous in enterprise environments.
The technical exploitation of this vulnerability requires an attacker to craft malicious X.509 certificates that trigger the specific memory corruption scenario during verification. When a vulnerable application processes such certificates, the double free condition can result in memory corruption that may be leveraged to execute arbitrary code with the privileges of the affected application. The vulnerability is particularly dangerous because it can be triggered during normal certificate validation operations, meaning that any network service that validates certificates could be compromised. Attackers could potentially craft certificates that, when presented to a vulnerable system, cause the double free condition to occur. This could lead to a range of outcomes from denial of service to full system compromise depending on the specific implementation and execution environment. The vulnerability affects both client and server applications since both components perform certificate verification during secure communication establishment. The exploitation process typically involves sending specially crafted certificates to a target system that uses GnuTLS for certificate validation, causing the memory corruption that can be leveraged for malicious purposes. The vulnerability demonstrates how cryptographic libraries, which are fundamental to secure communications, can contain flaws that undermine the security of entire systems. This issue highlights the importance of proper memory management in security-critical software components and the potential for seemingly minor implementation flaws to create significant security risks.
Organizations affected by this vulnerability should immediately implement mitigations to protect their systems and applications. The primary and most effective mitigation is to upgrade to GnuTLS version 3.6.7 or later, which contains the necessary patches to address the double free condition. System administrators should conduct comprehensive inventory assessments to identify all applications and services that rely on vulnerable GnuTLS versions, particularly those handling certificate validation. Security teams should implement monitoring solutions to detect potential exploitation attempts and establish incident response procedures for handling vulnerability remediation. Additionally, organizations should consider implementing certificate pinning mechanisms as a defensive measure to reduce the impact of certificate-based attacks. The vulnerability serves as a reminder of the importance of maintaining up-to-date cryptographic libraries and implementing proper security testing procedures. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of exploitation. Regular security assessments and vulnerability scanning should be conducted to identify other potential issues in the cryptographic infrastructure. The remediation process should include thorough testing of updated libraries to ensure compatibility with existing applications and services. This vulnerability underscores the critical nature of supply chain security and the responsibility of maintaining secure dependencies in software systems. The issue also highlights the importance of following security best practices such as the principle of least privilege and defense in depth. Organizations should establish processes for rapid response to security advisories and maintain updated threat intelligence to better protect against similar vulnerabilities in the future. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and execution techniques, emphasizing the potential for exploitation to achieve unauthorized system access.