CVE-2019-14575 in EDK II
Summary
by MITRE • 11/23/2020
Logic issue in DxeImageVerificationHandler() for EDK II may allow an authenticated user to potentially enable escalation of privilege via local access.
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Analysis
by VulDB Data Team • 12/10/2020
The vulnerability identified as CVE-2019-14575 represents a logic flaw within the DxeImageVerificationHandler() function of the EDK II firmware development environment. This issue specifically affects the secure boot verification process that occurs during the UEFI firmware initialization phase. The flaw exists in how the firmware handles image verification during the DXE (Driver Execution Environment) phase, creating a potential pathway for privilege escalation when an authenticated user has local access to the system. The vulnerability stems from insufficient validation of image signatures and verification states, allowing malicious code to bypass security checks that should prevent unauthorized firmware modifications.
The technical implementation of this vulnerability lies in the improper handling of image verification contexts within the DXE driver environment. When DxeImageVerificationHandler() processes firmware images, it fails to properly validate the security state of the verification handler itself, potentially allowing an attacker to manipulate the verification process. This logic error creates a condition where authenticated users can exploit the verification handler to load malicious code that would otherwise be rejected by the secure boot mechanism. The flaw is particularly concerning because it operates within the firmware layer where code execution can occur before the operating system has fully initialized, making it a critical point for privilege escalation attacks.
From an operational perspective, this vulnerability poses significant risk to systems relying on UEFI secure boot for protection. An authenticated user with local access can leverage this weakness to escalate privileges from user-level to administrator or firmware-level access. The attack vector requires physical or local access to the system, but once exploited, it can enable complete system compromise through firmware-level modifications. The impact extends beyond simple privilege escalation as it allows attackers to bypass hardware-level security features, potentially enabling persistent backdoors or complete system takeover. This vulnerability affects systems using EDK II-based firmware implementations, which are widely used in enterprise and government systems, making the potential impact substantial across various security-sensitive deployments.
Mitigation strategies for CVE-2019-14575 should focus on implementing proper firmware updates from vendors that address the logic flaw in DxeImageVerificationHandler(). System administrators should ensure that all firmware components are kept current with the latest security patches, particularly those addressing UEFI secure boot mechanisms. The vulnerability aligns with CWE-284 Access Control Issues and can be mapped to ATT&CK technique T1068 Privilege Escalation through the use of local system access to manipulate firmware verification processes. Organizations should implement additional monitoring for unusual firmware loading activities and ensure that secure boot policies are properly enforced at the firmware level. Regular security assessments of UEFI implementations should include verification of the integrity of image verification handlers to prevent exploitation of similar logic flaws in other firmware components.