CVE-2025-21213: Windows 10 1507 Secure Boot Bypass Flaw

CVE-2025-21213 Overview

CVE-2025-21213 is a Secure Boot Security Feature Bypass vulnerability affecting a wide range of Microsoft Windows operating systems. This vulnerability allows an attacker with physical access to a vulnerable system to bypass Secure Boot protections, potentially compromising the integrity of the boot process and enabling unauthorized code execution during system startup.

Secure Boot is a critical security feature designed to ensure that only trusted, digitally signed software can load during the boot process. By bypassing this mechanism, attackers could load malicious bootloaders or rootkits that persist below the operating system level, making detection and remediation extremely difficult.

Critical Impact
Physical attackers can bypass Secure Boot protections to load unauthorized code during system startup, potentially enabling persistent rootkit installation and full system compromise.

Affected Products

Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 22H2, 23H2, 24H2)
Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2022 23H2, and 2025

Discovery Timeline

January 14, 2025 - CVE-2025-21213 published to NVD
January 27, 2025 - Last updated in NVD database

Technical Details for CVE-2025-21213

Vulnerability Analysis

This vulnerability falls under the category of Secure Boot Bypass (CWE-284: Improper Access Control). The flaw enables an attacker with physical access to circumvent the Secure Boot verification process, which normally ensures that only properly signed and trusted code can execute during the boot phase.

The attack requires physical access to the target system, limiting the attack surface compared to remotely exploitable vulnerabilities. However, the potential impact is significant because successful exploitation can lead to high confidentiality impact, allowing attackers to access sensitive information protected by boot-level security mechanisms.

Organizations with high-value assets, shared computing environments, or systems in physically accessible locations should prioritize addressing this vulnerability. Environments such as kiosks, shared workstations, data centers with contractor access, and systems subject to supply chain attacks are at elevated risk.

Root Cause

The vulnerability stems from improper access control (CWE-284) within the Windows Secure Boot implementation. The specific mechanism allows the boot process validation to be bypassed under certain conditions when an attacker has physical access to the system. This represents a failure in the trust chain that Secure Boot is designed to enforce, where the firmware should verify each component before allowing it to execute.

Attack Vector

The attack vector requires physical access to the vulnerable system. An attacker must be able to interact directly with the hardware to exploit this vulnerability. The attack complexity is low, meaning that once physical access is obtained, exploitation does not require specialized conditions or extensive technical knowledge.

The attack scenario involves an attacker with physical access manipulating the boot process to bypass Secure Boot verification. This could be accomplished through various methods such as modifying boot media, exploiting firmware interfaces, or leveraging specific hardware features. No user interaction is required, and the attacker does not need prior privileges on the system.

Successful exploitation results in high confidentiality impact, potentially exposing sensitive data protected by Secure Boot mechanisms, including encryption keys, credentials, and other secrets stored in secure enclaves or protected by boot-time security features.

Detection Methods for CVE-2025-21213

Indicators of Compromise

Unexpected changes to UEFI/BIOS settings or boot configuration data
Modified or unsigned boot components detected during integrity verification
Anomalous system behavior during startup or unexpected boot delays
Evidence of physical tampering with hardware or boot media

Detection Strategies

Enable and monitor Secure Boot violation events in Windows Event Log (Event ID 1033 in Microsoft-Windows-EFI)
Implement measured boot with TPM attestation to detect boot integrity violations
Deploy endpoint detection solutions capable of monitoring pre-boot and boot-time activities
Regularly verify boot component signatures and compare against known-good baselines

Monitoring Recommendations

Configure alerts for Secure Boot-related events in your SIEM solution
Implement physical security controls and access logging for sensitive systems
Enable BitLocker with TPM+PIN to add additional boot-time protection layers
Conduct regular firmware integrity checks and compare against vendor baselines

How to Mitigate CVE-2025-21213

Immediate Actions Required

Apply Microsoft security updates released in January 2025 for all affected Windows versions
Review physical access controls for systems in shared or accessible environments
Enable BitLocker with TPM and PIN authentication for additional boot protection
Audit systems for signs of physical tampering or unauthorized boot modifications

Patch Information

Microsoft has released security updates to address CVE-2025-21213 across all affected Windows versions. Administrators should consult the Microsoft Security Update Guide for CVE-2025-21213 for specific patch details and download links for each affected product version. Updates should be tested in non-production environments before deployment and applied through established patch management processes.

Workarounds

Implement strict physical security controls to limit access to vulnerable systems
Enable Credential Guard and Device Guard features where supported
Configure BitLocker with TPM+PIN or startup key requirements to add boot authentication
Deploy chassis intrusion detection and alerting for critical systems
Consider network isolation for systems that cannot be immediately patched

bash

# Verify Secure Boot status on Windows systems
Confirm-SecureBootUEFI

# Check BitLocker protection status
manage-bde -status C:

# Enable measured boot logging for detection
bcdedit /set {bootmgr} measuredsystemstartinputcritical Yes