CVE-2015-8892 in Android
Summary
by MITRE
platform/msm_shared/boot_verifier.c in the Qualcomm components in Android before 2016-07-05 on Nexus 5X and 6P devices allows attackers to bypass intended access restrictions via a digest with trailing data, aka Android internal bug 28822807 and Qualcomm internal bug CR902998.
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Analysis
by VulDB Data Team • 09/01/2022
The vulnerability described in CVE-2015-8892 represents a critical security flaw in the Android operating system's boot verification mechanism on specific Qualcomm-powered devices. This issue affects Nexus 5X and 6P devices running Android versions prior to the 2016-07-05 security patch release, where the Qualcomm components contain a weakness in the platform/msm_shared/boot_verifier.c file. The flaw enables attackers to circumvent intended access controls through a specific manipulation technique involving digest verification with trailing data, which constitutes a significant bypass of the system's integrity protection mechanisms.
The technical implementation of this vulnerability stems from improper handling of cryptographic digest verification within the boot process. The boot verifier component is designed to ensure that only authorized and unmodified system components can execute during the device's startup sequence, thereby maintaining the integrity of the entire operating system. However, the flaw occurs when the system processes cryptographic digests that contain additional trailing data beyond the expected digest length. This condition allows attackers to craft malicious payloads that pass the verification checks while still containing unauthorized modifications, effectively undermining the cryptographic security measures that protect against unauthorized system modifications.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the device's ability to verify system integrity during the boot process. Attackers can exploit this weakness to install malicious software that bypasses the normal security checks, potentially enabling root access to the device and full control over the system's operations. This vulnerability particularly affects the Android Security Model's integrity protection layer, where the boot verification process serves as the first line of defense against malicious code execution. The exploitation of this flaw can lead to complete device compromise, data theft, and the installation of persistent backdoors that remain operational across device reboots.
Mitigation strategies for this vulnerability require immediate implementation of the security patches released by Google and Qualcomm, specifically targeting the Android 2016-07-05 update for affected Nexus devices. Organizations and users must ensure their devices receive the appropriate firmware updates that address the digest verification flaw in the boot verifier component. The fix involves strengthening the digest validation process to properly handle trailing data and prevent the bypass of cryptographic checks. Additionally, system administrators should implement monitoring for unauthorized device modifications and maintain strict device management policies, particularly for enterprise environments where the security implications of such vulnerabilities could be severe. This vulnerability aligns with CWE-295 which addresses improper certificate validation and relates to ATT&CK technique T1014 which covers rootkit creation and persistence mechanisms. The issue demonstrates how weaknesses in low-level system components can create fundamental security breaches that affect the entire operating system's trust model and highlight the importance of robust cryptographic verification in critical system processes.