CVE-2016-0807 in Android
Summary
by MITRE
The get_build_id function in elf_utils.cpp in Debuggerd in Android 6.x before 2016-02-01 allows attackers to gain privileges via a crafted application that mishandles a Desc Size element in an ELF Note, aka internal bug 25187394.
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Analysis
by VulDB Data Team • 07/23/2018
The vulnerability described in CVE-2016-0807 resides within the debuggerd component of Android 6.0 systems, specifically in the elf_utils.cpp file where the get_build_id function processes ELF notes. This flaw represents a critical privilege escalation vulnerability that affects devices running Android 6.0 before the 2016-02-01 security patch release. The vulnerability stems from improper handling of the Desc Size element within ELF Notes, which are metadata structures embedded in executable files that provide information about the binary. When an attacker crafts a malicious application containing malformed ELF Note structures, the debuggerd component fails to properly validate the descriptor size field, creating a potential exploitation vector.
The technical implementation of this vulnerability involves a buffer overflow condition that occurs during the parsing of ELF note sections. The get_build_id function does not adequately validate the size parameter of the descriptor field within the ELF note structure, allowing attackers to specify an oversized descriptor size that exceeds the allocated buffer boundaries. This improper validation creates a situation where the debuggerd process can be tricked into writing beyond the intended memory boundaries, potentially leading to arbitrary code execution or privilege escalation. The flaw operates at the kernel level within the debugging subsystem, making it particularly dangerous as it can be exploited by malicious applications without requiring root access initially.
From an operational perspective, this vulnerability presents a significant risk to Android 6.0 devices that were not patched before the 2016-02-01 release date. Attackers can leverage this weakness to execute malicious code with elevated privileges, potentially gaining access to sensitive system resources and user data. The impact extends beyond individual device compromise to potential widespread exploitation across affected Android versions, particularly in environments where users may not regularly update their systems. This vulnerability directly relates to CWE-121, which describes stack-based buffer overflow conditions, and aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' by exploiting weaknesses in system processes.
The mitigation strategy for this vulnerability requires immediate deployment of the security patch released by Google in February 2016, which addresses the improper validation of ELF note descriptor sizes within the debuggerd component. Organizations should ensure all Android 6.0 devices are updated to the latest security patches, with particular attention to devices that may not automatically receive updates. Additionally, system administrators should implement monitoring for suspicious application behavior and consider network-level controls to prevent the execution of potentially malicious applications that could exploit this vulnerability. The fix implemented by Google involved strengthening input validation within the get_build_id function to properly check the descriptor size field against expected ranges, preventing the buffer overflow condition that enabled privilege escalation. This vulnerability underscores the importance of robust input validation in system-level components and demonstrates how seemingly minor flaws in debugging utilities can create significant security risks across entire operating system ecosystems.