CVE-2015-8893 in Android
Summary
by MITRE
app/aboot/aboot.c in the Qualcomm bootloader in Android before 2016-07-05 on Nexus 5 and 7 (2013) devices allows attackers to cause a denial of service (OS outage or buffer over-read) via a crafted application, aka Android internal bug 28822690 and Qualcomm internal bug CR822275.
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Analysis
by VulDB Data Team • 09/01/2022
The vulnerability CVE-2015-8893 resides within the Qualcomm bootloader component known as aboot.c, which operates as a critical firmware element in Android devices including the Nexus 5 and Nexus 7 (2013) models. This flaw exists in the bootloader implementation that governs the initial system startup process and firmware validation procedures. The vulnerability manifests when a malicious application is executed on the device, potentially causing the operating system to experience an outage or buffer over-read condition that disrupts normal system operation. The issue was particularly concerning as it affected devices running Android versions prior to the 2016-07-05 security update cycle, leaving millions of devices vulnerable to potential exploitation. This vulnerability represents a fundamental weakness in the boot process security model where malicious code can directly target the bootloader level, bypassing traditional application sandboxing mechanisms that typically protect user applications from critical system components.
The technical implementation of this vulnerability stems from improper input validation within the aboot.c bootloader code that handles application loading sequences. When a crafted application is executed, it can manipulate memory structures within the bootloader context, leading to buffer over-read conditions where the bootloader attempts to access memory locations beyond allocated buffers. This type of flaw falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions, though the nature of the bootloader environment creates a more severe impact than typical user-space buffer overflows. The vulnerability allows attackers to potentially trigger memory corruption that can result in system crashes, complete OS outages, or in more sophisticated exploitation scenarios, could provide a foothold for further system compromise. The exploitation mechanism leverages the fact that bootloader components typically operate with elevated privileges and have direct access to hardware resources, making them attractive targets for attackers seeking persistent system control.
The operational impact of CVE-2015-8893 extends beyond simple denial of service conditions, as it represents a significant security weakness in the device's boot integrity chain. When exploited, this vulnerability can render affected devices unusable or cause them to enter unstable states where normal boot sequences fail to complete successfully. The vulnerability affects the Android security model by undermining the trust model that relies on secure boot processes to validate system integrity before allowing normal operation. This particular flaw was classified as a critical issue because it operates at the bootloader level, which is typically considered the most privileged execution environment in mobile devices. The vulnerability affects a substantial user base including Nexus 5 and Nexus 7 (2013) devices that were widely deployed and used in enterprise and consumer environments. Organizations relying on these devices for critical operations faced potential security risks where unauthorized users could potentially cause system outages or create conditions that might enable more sophisticated attacks through subsequent exploitation vectors.
The mitigation strategies for CVE-2015-8893 primarily involve applying the security patches released by Google as part of the Android security update cycle, specifically targeting the 2016-07-05 update release. Device manufacturers and system administrators should ensure that all affected devices receive the appropriate firmware updates that address the bootloader memory handling issues. The patch implementation typically involves correcting the input validation procedures within the aboot.c code to properly handle buffer boundaries and prevent over-read conditions during application loading processes. Additionally, organizations should implement device management policies that enforce timely security updates and maintain inventory tracking of affected devices. From an ATT&CK framework perspective, this vulnerability relates to techniques involving privilege escalation and boot process manipulation, as attackers can leverage this flaw to compromise the device's integrity before normal operating system security mechanisms are fully initialized. The vulnerability also highlights the importance of secure boot chain validation and demonstrates how weaknesses in early boot components can undermine the entire security architecture of mobile platforms, emphasizing the need for comprehensive security testing across all system layers including firmware and bootloader implementations.