CVE-2016-2494 in Android
Summary
by MITRE
Off-by-one error in sdcard/sdcard.c in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-06-01 allows attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 28085658.
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Analysis
by VulDB Data Team • 06/07/2024
The vulnerability identified as CVE-2016-2494 represents a critical off-by-one error within the Android storage subsystem, specifically in the sdcard/sdcard.c component that governs the secure card management functionality. This flaw exists across multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before the specified patch date, creating a persistent security weakness that affects a substantial portion of Android devices. The vulnerability operates at the kernel level within the Android framework, where improper bounds checking in the storage card handling code creates a condition that can be exploited by malicious applications to escalate their privileges.
The technical nature of this vulnerability stems from an off-by-one error, a common programming flaw classified under CWE-129, where the boundary checking logic fails to properly validate array or buffer access. In this case, the error occurs within the sdcard implementation where the system incorrectly handles the boundary conditions for storage card operations. Attackers can craft malicious applications that exploit this condition to manipulate memory boundaries, ultimately allowing them to bypass the normal security restrictions that typically prevent applications from accessing system-level resources. The exploitation mechanism specifically targets the privilege escalation pathways that should normally restrict applications to their designated sandboxed environments, enabling attackers to obtain either Signature-level or SignatureOrSystem access privileges.
The operational impact of this vulnerability is severe as it allows attackers to gain elevated privileges that would normally be restricted to system applications or those with specific signature-level permissions. This privilege escalation capability means that a malicious application could potentially access sensitive system resources, modify critical system files, or even install additional malware with system-level privileges. The vulnerability's exploitation demonstrates a significant breach in Android's security model, particularly in the context of the ATT&CK framework where this would be classified under privilege escalation techniques. The ability to achieve Signature or SignatureOrSystem access represents a critical compromise of Android's application security model, as these access levels provide extensive control over system resources and data.
The mitigation strategies for this vulnerability require immediate patching of affected Android versions, with the most effective approach being the installation of the security updates released by Google and device manufacturers. Organizations should prioritize updating all Android devices to versions that contain the patched sdcard implementation, specifically targeting the versions that address the off-by-one error in the storage subsystem. System administrators should also implement monitoring for suspicious application behavior that might indicate exploitation attempts, as well as maintain updated threat intelligence feeds that track related malware variants. The vulnerability highlights the importance of rigorous code review processes and boundary checking in system-level components, particularly those handling file system operations and privilege management. Device manufacturers and carriers must ensure rapid deployment of security patches to protect their user base, as the extended timeframe between vulnerability disclosure and patch availability increases the risk of exploitation in the wild. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches across all Android devices and the potential consequences of delayed remediation efforts.