CVE-2008-3893 in Windows
Summary
by MITRE
Microsoft Bitlocker in Windows Vista before SP1 stores pre-boot authentication passwords in the BIOS Keyboard buffer and does not clear this buffer during boot, which allows local users to obtain sensitive information by reading the physical memory locations associated with this buffer.
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Analysis
by VulDB Data Team • 04/03/2025
Microsoft BitLocker Drive Encryption implemented in Windows Vista before Service Pack 1 contains a critical security flaw that stems from improper handling of pre-boot authentication credentials within the system firmware. The vulnerability specifically affects how the BitLocker implementation manages the BIOS keyboard buffer during the boot process, creating a persistent security risk that can be exploited by local attackers with physical access to the affected system. This issue represents a fundamental failure in the secure credential management architecture that violates established security principles for protecting sensitive authentication data.
The technical flaw manifests when BitLocker stores the pre-boot authentication password in the BIOS keyboard buffer, a memory region that should be cleared immediately after the authentication process completes. However, the Windows Vista implementation fails to properly clear this buffer during the boot sequence, leaving the sensitive password information accessible in physical memory locations. This design oversight creates a persistent exposure window where any local attacker with sufficient privileges and physical access can potentially extract the stored credentials by directly reading the memory locations associated with the BIOS keyboard buffer. The vulnerability operates at a low system level, making it particularly challenging to detect and mitigate through conventional security measures.
The operational impact of this vulnerability extends beyond simple credential theft, as it fundamentally undermines the security model of BitLocker encryption. Attackers can leverage this weakness to bypass the pre-boot authentication process entirely, effectively rendering the encryption protection meaningless for systems running vulnerable versions of Windows Vista. This exposure creates a significant risk for organizations that rely on BitLocker for data protection, particularly in environments where physical security controls may be inadequate or where insider threats exist. The vulnerability also demonstrates a broader failure in the secure handling of sensitive information during system boot processes, affecting not just BitLocker but potentially other encryption and authentication mechanisms that depend on similar memory management approaches.
Organizations should immediately implement mitigations including upgrading to Windows Vista Service Pack 1 or later versions that address this specific vulnerability, as well as implementing additional physical security controls to prevent unauthorized access to systems during the boot process. The flaw aligns with CWE-254, which addresses weaknesses in the security model of authentication systems, and represents a critical gap in the ATT&CK framework's credential access techniques, specifically targeting the use of system memory for credential harvesting. Security professionals should also consider implementing additional monitoring solutions that can detect unauthorized memory access patterns and establish robust physical security protocols to prevent exploitation of this vulnerability in production environments.