CVE-2018-8930 in EPYC Server
Summary
by MITRE
The AMD EPYC Server, Ryzen, Ryzen Pro, and Ryzen Mobile processor chips have insufficient enforcement of Hardware Validated Boot, aka MASTERKEY-1, MASTERKEY-2, and MASTERKEY-3.
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Analysis
by VulDB Data Team • 01/16/2020
The vulnerability identified as CVE-2018-8930 affects AMD EPYC Server, Ryzen, Ryzen Pro, and Ryzen Mobile processor chips, representing a critical weakness in the hardware validated boot process. This flaw manifests through insufficient enforcement of the Hardware Validated Boot mechanism, which is designed to ensure that only trusted firmware and operating system components can execute during system startup. The vulnerability has been categorized under the broader MASTERKEY-1, MASTERKEY-2, and MASTERKEY-3 designations, indicating a systematic weakness in AMD's processor architecture that impacts multiple product lines. The issue resides in the fundamental boot process validation that should prevent unauthorized code execution before the operating system loads, creating a potential entry point for sophisticated attackers seeking to compromise system integrity.
The technical flaw stems from inadequate implementation of the Hardware Validated Boot protocol within AMD's processor silicon, where the system fails to properly validate the integrity of boot components before execution. This weakness allows for potential manipulation of the boot process through techniques such as bootkit attacks or firmware modifications that bypass normal security checks. The vulnerability specifically impacts the processor's ability to enforce secure boot policies, creating opportunities for attackers to inject malicious code into the system before the operating system can establish its own security controls. This represents a direct violation of the principle of least privilege and trust verification that should occur during system initialization, as the processor fails to maintain proper cryptographic validation of boot components.
The operational impact of this vulnerability extends beyond simple system compromise, as it enables attackers to establish persistent footholds within target environments through undetected boot-level modifications. Attackers can leverage this weakness to deploy rootkits, bootkits, or other malicious software that operates below the detection capabilities of traditional operating system security mechanisms. The implications are particularly severe for enterprise environments where these processors are deployed, as the vulnerability could enable attackers to maintain long-term access to systems while evading standard security monitoring tools. This weakness fundamentally undermines the security assurances that organizations expect from their hardware platforms, particularly in scenarios where system integrity and trust are paramount.
Mitigation strategies for CVE-2018-8930 should focus on both firmware updates and system configuration adjustments to address the hardware-level validation failures. Organizations should implement comprehensive firmware update programs targeting affected AMD processors, ensuring that all available security patches are deployed across their infrastructure. Additionally, system administrators should consider implementing additional boot integrity monitoring solutions that can detect unauthorized modifications to the boot process, as the hardware validation mechanism itself has been compromised. The vulnerability aligns with CWE-284, which addresses inadequate access control, and maps to ATT&CK technique T1068, which covers local privilege escalation through bootkit manipulation. Organizations should also consider implementing hardware security modules and secure boot enforcement mechanisms that provide additional layers of protection beyond the vulnerable hardware validation process, as the fundamental issue requires remediation at the processor level through firmware updates from AMD.