CVE-2016-0849 in Android
Summary
by MITRE
Multiple integer overflows in minzip/SysUtil.c in the Recovery Procedure in Android 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-04-01 allow attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 26960931.
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Analysis
by VulDB Data Team • 07/12/2022
The vulnerability identified as CVE-2016-0849 represents a critical integer overflow flaw within the Android recovery procedure mechanism, specifically located in the minzip/SysUtil.c component of the Android operating system. This vulnerability affects multiple Android versions including Android 5.0.x before 5.0.2, 5.1.x before 5.1.1, and Android 6.x before the 2016-04-01 security patch release. The flaw occurs during the processing of zip files within the recovery environment, where improper integer overflow handling creates opportunities for privilege escalation attacks. The vulnerability is particularly concerning because it operates within the recovery procedure context, which is a critical system component that typically runs with elevated privileges and has access to system-level operations.
The technical implementation of this vulnerability stems from inadequate input validation and integer overflow protection within the zip file processing logic of the recovery environment. When a malicious application attempts to exploit this flaw, it can manipulate the integer values used for buffer calculations, leading to memory corruption that allows attackers to bypass normal access controls. The specific nature of the vulnerability enables attackers to obtain Signature or SignatureOrSystem access levels, which represent significant privilege escalation capabilities within the Android security model. This access level allows the attacker to operate with the same privileges as system applications that require signature-level permissions, effectively breaking the application sandboxing model. The integer overflow occurs during the calculation of buffer sizes or array indices when processing specially crafted zip archives, causing the system to allocate insufficient memory or access memory regions outside the intended boundaries.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the ability to execute malicious code with elevated privileges within the recovery environment. This environment is particularly significant because it operates outside the normal application execution context and has access to critical system resources and functions. Attackers can leverage this vulnerability to install malicious applications, modify system files, or even replace the operating system itself. The recovery procedure environment is designed to be accessible when the system is in a compromised state, making this vulnerability particularly dangerous as it can be exploited even when the device is running normally. The vulnerability's exploitation requires a crafted application that specifically targets the zip file processing logic, making it a targeted attack vector rather than a broad-based exploit. This characteristic aligns with the ATT&CK framework's privilege escalation techniques, specifically targeting system-level access and command execution capabilities.
Mitigation strategies for CVE-2016-0849 primarily focus on applying the appropriate security patches released by Google as part of their regular security updates. Organizations and users must ensure that all affected Android devices receive the security updates released before 2016-04-01, which address the integer overflow conditions in the recovery procedure processing. The vulnerability's classification as a CWE-190 integer overflow represents a well-known weakness in software development practices, particularly in the handling of unsigned integer arithmetic and buffer size calculations. System administrators should implement comprehensive patch management procedures to ensure timely application of security fixes across all Android devices within their environment. Additionally, mobile device management solutions should be configured to monitor for and block potentially malicious applications that attempt to exploit this vulnerability, particularly those that manipulate zip file structures or attempt to access system-level resources. The vulnerability demonstrates the importance of secure coding practices and input validation in system-level components, particularly those that operate with elevated privileges and handle untrusted data from external sources.