CVE-2015-8888 in Android
Summary
by MITRE
Integer overflow in app/aboot/aboot.c in the Qualcomm components in Android before 2016-07-05 on Nexus 5 devices allows attackers to bypass intended access restrictions via a crafted block count and block size of a sparse header, aka Android internal bug 28822465 and Qualcomm internal bug CR813933.
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Analysis
by VulDB Data Team • 09/01/2022
The vulnerability identified as CVE-2015-8888 represents a critical integer overflow condition within the Qualcomm bootloader component of Android operating systems, specifically affecting Nexus 5 devices prior to the 2016-07-05 security patch release. This flaw exists in the aboot.c file within the app/aboot/ directory structure, which governs the boot process and handles sparse image headers during device initialization. The vulnerability stems from improper validation of block count and block size parameters within sparse header structures, creating a scenario where attackers can manipulate these values to trigger arithmetic overflow conditions that compromise the intended access controls.
The technical implementation of this vulnerability involves the manipulation of sparse image headers used during Android device boot processes, particularly those associated with the Qualcomm bootloader. When the system processes a crafted sparse header containing manipulated block count and block size values, the integer overflow occurs during calculations that determine memory allocation or buffer boundaries. This overflow can result in the system treating the manipulated values as if they were much larger than intended, potentially allowing unauthorized access to memory regions that should remain protected. The vulnerability specifically targets the Qualcomm components integrated into Android's boot process, making it particularly dangerous as it operates at a low-level system component that controls device initialization and access restrictions.
The operational impact of CVE-2015-8888 extends beyond simple privilege escalation, as it enables attackers to bypass fundamental access controls that protect critical system components and data. This vulnerability can be exploited to gain unauthorized access to protected memory regions, potentially allowing for the execution of arbitrary code during the boot process or the modification of system files that should remain inaccessible. The attack vector requires a crafted sparse image header that can be delivered through various means including malicious firmware updates, USB-based attacks, or compromised installation media. The vulnerability's exploitation can result in complete system compromise, enabling attackers to install persistent backdoors, modify bootloaders, or access sensitive cryptographic keys and user data stored on the device.
Security mitigations for CVE-2015-8888 primarily involve applying the Android security patches released on or after July 5, 2016, which address the integer overflow condition in the Qualcomm bootloader components. Organizations should ensure all Nexus 5 devices receive the appropriate updates and implement proper firmware verification mechanisms to prevent unauthorized modifications. The vulnerability aligns with CWE-190, which describes integer overflow conditions, and represents a classic example of how low-level bootloader components can create persistent security weaknesses that affect entire device ecosystems. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and boot process manipulation, specifically targeting the boot integrity and system initialization phases where adversaries can establish persistent access to compromised devices. The flaw demonstrates the critical importance of input validation in system-level components and the potential for seemingly minor arithmetic errors to create significant security implications in embedded systems and mobile platforms.