CVE-2015-2552 in Windows
Summary
by MITRE
The kernel in Microsoft Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT Gold and 8.1, and Windows 10 allows physically proximate attackers to bypass the Trusted Boot protection mechanism, and consequently interfere with the integrity of code, BitLocker, Device Encryption, and Device Health Attestation, via a crafted Boot Configuration Data (BCD) setting, aka "Trusted Boot Security Feature Bypass Vulnerability."
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Analysis
by VulDB Data Team • 06/20/2022
The vulnerability described in CVE-2015-2552 represents a critical flaw in Microsoft Windows kernel security mechanisms that undermines fundamental trusted computing protections. This vulnerability specifically targets the Trusted Boot process which is designed to ensure that only authentic and unmodified code executes during system boot, thereby maintaining the integrity of critical security features including BitLocker encryption, Device Encryption, and Device Health Attestation. The flaw allows attackers with physical access to a target system to manipulate boot configuration data and bypass these essential security protections, effectively nullifying the security assurances that users expect from their operating systems. This issue affects multiple Windows versions including Windows 8, 8.1, Server 2012, RT, and Windows 10, demonstrating the widespread impact of this kernel-level vulnerability.
The technical exploitation of this vulnerability occurs through manipulation of the Boot Configuration Data (BCD) settings, which are critical components that control how the operating system boots and initializes security features. Attackers can craft specific BCD modifications that trick the Trusted Boot mechanism into accepting compromised boot components, thereby allowing malicious code to execute with elevated privileges before the system can properly validate its integrity. This bypass mechanism operates at the kernel level, making it particularly dangerous as it can circumvent multiple security layers including the Secure Boot process, which is designed to prevent unauthorized code execution during the boot sequence. The vulnerability specifically leverages weaknesses in how the kernel validates boot configuration parameters, allowing for modification of trusted boot paths without proper authentication or verification.
The operational impact of CVE-2015-2552 extends far beyond simple privilege escalation, as it fundamentally compromises the security posture of affected systems by undermining core encryption and attestation mechanisms. When Trusted Boot is bypassed, BitLocker encryption becomes vulnerable to attacks that could potentially allow unauthorized access to encrypted data, while Device Encryption protection is similarly compromised. Device Health Attestation, which is crucial for verifying device integrity in enterprise security scenarios, becomes ineffective as attackers can manipulate the boot process to present false attestation reports. This vulnerability particularly affects enterprise environments where device security and data protection are paramount, as it allows attackers to undermine security policies and potentially gain access to sensitive corporate information. The physical proximity requirement limits the attack surface but does not eliminate the threat, as many enterprise environments have systems that are accessible to unauthorized individuals in secure locations.
Organizations affected by this vulnerability should implement immediate mitigations including updating to patched versions of Windows operating systems, which Microsoft released as part of their regular security updates. System administrators should also consider implementing additional physical security controls to limit unauthorized access to systems, particularly in environments where sensitive data is stored. The vulnerability aligns with CWE-1103, which describes weaknesses in trusted boot mechanisms, and represents a significant concern in the ATT&CK framework under the T1068 technique for "Exploitation for Privilege Escalation." Organizations should also consider implementing monitoring for suspicious BCD modifications and establishing robust incident response procedures to detect potential exploitation attempts. The long-term solution involves maintaining up-to-date security patches and ensuring that all systems are running patched versions of the operating system to prevent exploitation of this kernel-level vulnerability.