CVE-2018-8356 in .NET Framework
Summary
by MITRE
A security feature bypass vulnerability exists when Microsoft .NET Framework components do not correctly validate certificates, aka ".NET Framework Security Feature Bypass Vulnerability." This affects .NET Framework 4.7.2, Microsoft .NET Framework 3.0, Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2, ASP.NET Core 1.1, Microsoft .NET Framework 4.5.2, ASP.NET Core 2.0, ASP.NET Core 1.0, .NET Core 1.1, Microsoft .NET Framework 3.5, Microsoft .NET Framework 3.5.1, Microsoft .NET Framework 4.6/4.6.1/4.6.2, .NET Core 1.0, .NET Core 2.0, Microsoft .NET Framework 4.6, Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.1/4.7.2, Microsoft .NET Framework 4.7.2.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/06/2023
The CVE-2018-8356 vulnerability represents a critical security feature bypass flaw within Microsoft .NET Framework components that fundamentally undermines certificate validation mechanisms. This vulnerability stems from improper certificate validation processes within the .NET Framework runtime, creating a pathway for attackers to circumvent essential security controls that should prevent unauthorized access to protected resources. The flaw specifically affects multiple versions of the .NET Framework and ASP.NET Core implementations, spanning from version 3.0 through 4.7.2, alongside various .NET Core releases including 1.0, 1.1, and 2.0. The vulnerability's impact extends across enterprise environments where .NET applications handle sensitive data, authentication processes, and secure communications, making it particularly dangerous for organizations relying on these frameworks for mission-critical operations.
The technical root cause of this vulnerability lies in the flawed certificate validation logic that fails to properly enforce security checks during the certificate chain validation process. When .NET Framework components process certificates, they do not adequately validate the certificate authorities, expiration dates, or cryptographic signatures that should normally prevent the acceptance of invalid or malicious certificates. This allows attackers to exploit the validation bypass by presenting certificates that would normally be rejected by the system, potentially enabling man-in-the-middle attacks, unauthorized access to encrypted communications, and impersonation of legitimate services. The vulnerability specifically relates to how the framework handles certificate trust relationships and certificate revocation checking, creating opportunities for attackers to manipulate the security decision-making process within applications.
The operational impact of CVE-2018-8356 is substantial across enterprise environments, as it can enable attackers to establish unauthorized secure connections, intercept encrypted communications, and potentially gain access to sensitive data that should remain protected. Organizations running applications built on affected .NET Framework versions face increased risk of data breaches, credential theft, and service disruption when this vulnerability is exploited. The broad scope of affected versions means that many legacy systems and modern applications could be vulnerable, creating extensive attack surface exposure. Security teams must consider the potential for this vulnerability to be leveraged in advanced persistent threat campaigns where attackers seek to maintain long-term access to networks by bypassing standard certificate-based authentication mechanisms.
Mitigation strategies for CVE-2018-8356 should prioritize immediate deployment of Microsoft security patches and updates that address the certificate validation bypass. Organizations must conduct comprehensive inventory assessments to identify all systems running affected .NET Framework versions and prioritize remediation efforts accordingly. The vulnerability aligns with CWE-295 Certificate Validation Flaws, which specifically addresses improper certificate validation and trust management in security protocols. Additionally, organizations should implement network monitoring to detect anomalous certificate usage patterns and establish enhanced certificate management procedures that include regular validation of certificate chains and revocation checking. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and defense evasion, as attackers can bypass certificate-based security controls to maintain persistent access. Security architects should also consider implementing additional layers of protection such as application whitelisting, enhanced network segmentation, and regular security audits to prevent exploitation of this certificate validation bypass vulnerability.