CVE-2016-2424 in Android
Summary
by MITRE
server/content/SyncStorageEngine.java in SyncStorageEngine 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 2016-04-01 mismanages certain authority data, which allows attackers to cause a denial of service (reboot loop) via a crafted application, aka internal bug 26513719.
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Analysis
by VulDB Data Team • 07/12/2022
The vulnerability described in CVE-2016-2424 represents a critical flaw in Android's SyncStorageEngine component that affects multiple versions of the Android operating system from 4.x through 6.x. This issue resides within the server/content/SyncStorageEngine.java file and specifically concerns how the system handles authority data during synchronization processes. The flaw enables attackers to manipulate synchronization mechanisms in a way that triggers system instability, ultimately leading to denial of service conditions that can cause devices to enter continuous reboot loops. The vulnerability was internally tracked as bug 26513719, indicating its significance within Google's internal tracking systems. The affected versions include 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 the 2016-04-01 security update release, highlighting the widespread nature of this flaw across multiple Android generations. This vulnerability operates at the system level, affecting core synchronization functionality that manages data synchronization between applications and various system services.
The technical implementation of this vulnerability stems from improper management of authority data within the SyncStorageEngine component. When a malicious application crafts specific authority data and attempts to synchronize with the system, the engine fails to properly validate or handle these malformed inputs. This mismanagement creates a condition where the system's synchronization framework becomes corrupted or enters an inconsistent state. The flaw manifests as a recursive or circular dependency in the synchronization process where the system continuously attempts to process the malformed authority data, leading to an infinite loop that eventually results in a system crash. The vulnerability specifically exploits the way the system handles authority persistence and validation, allowing attackers to inject malicious data that causes the synchronization engine to malfunction. This type of flaw falls under CWE-248, which addresses "Uncaught Exception" conditions, and more specifically relates to improper handling of system-level data structures that control synchronization operations. The vulnerability demonstrates poor input validation and error handling practices within the Android framework's core synchronization mechanisms.
The operational impact of CVE-2016-2424 is severe and directly affects device availability and user experience. When exploited, the vulnerability causes devices to enter continuous reboot loops, effectively rendering them unusable until manually reset or the system is patched. This denial of service condition can be triggered remotely through malicious applications, making it particularly dangerous in environments where users may unknowingly install compromised applications. The attack vector requires only a single malicious application to be installed on the device, as the vulnerability is in the system's core synchronization mechanism rather than requiring special privileges or root access. This makes the vulnerability highly exploitable in real-world scenarios where users may encounter malicious applications through various distribution channels. The impact extends beyond individual device usability to potentially affect enterprise environments where multiple devices could be simultaneously compromised, leading to broader operational disruptions. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 - "Endpoint Denial of Service" and represents a system-level attack that targets fundamental Android services rather than application-level functionality.
Mitigation strategies for CVE-2016-2424 focus primarily on applying the appropriate security patches released by Google for the affected Android versions. Organizations should prioritize updating all Android devices to the latest security patches available for their respective Android versions, particularly targeting the specific build numbers that contain fixes for this vulnerability. System administrators should implement strict application vetting processes to prevent installation of untrusted applications that could exploit this vulnerability. Network-level monitoring should be enhanced to detect unusual synchronization patterns that might indicate exploitation attempts. Device manufacturers should ensure that security updates are deployed promptly to affected devices, as the vulnerability affects multiple generations of Android. The patch for this vulnerability specifically addresses the authority data handling within SyncStorageEngine, correcting the improper validation and error handling that allowed the malicious authority data to cause system instability. Security teams should also consider implementing device management policies that restrict synchronization permissions for applications and monitor for unusual system behavior that might indicate exploitation. Regular security assessments should verify that devices have been properly patched and that no legacy systems remain vulnerable to this attack vector.