CVE-2014-7953 in Android
Summary
by MITRE
Race condition in the bindBackupAgent method in the ActivityManagerService in Android 4.4.4 allows local users with adb shell access to execute arbitrary code or any valid package as system by running "pm install" with the target apk, and simultaneously running a crafted script to process logcat's output looking for a dexopt line, which once found should execute bindBackupAgent with the uid member of the ApplicationInfo parameter set to 1000.
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Analysis
by VulDB Data Team • 05/09/2022
The vulnerability described in CVE-2014-7953 represents a critical race condition within the Android operating system's ActivityManagerService component. This flaw exists specifically in Android 4.4.4 and manifests as a timing issue that can be exploited by local attackers who possess adb shell access. The vulnerability stems from improper synchronization mechanisms in the bindBackupAgent method, which creates an opportunity for privilege escalation through carefully orchestrated concurrent operations. The race condition occurs during the process of package installation and backup agent binding, where the system fails to properly validate or secure the state transition between these operations.
The technical exploitation of this vulnerability requires a sophisticated understanding of Android's internal processes and system architecture. Attackers must simultaneously execute two distinct operations: running the "pm install" command to install a target APK while concurrently executing a crafted script that monitors logcat output for specific patterns. The script must be designed to detect a dexopt line in the log output, which serves as a synchronization point for the exploit. Once this specific log entry is identified, the attacker's script must then execute the bindBackupAgent method with a carefully crafted ApplicationInfo parameter where the uid member is set to 1000, which corresponds to the system user ID in Android systems. This manipulation allows the attacker to effectively impersonate the system user during the backup agent binding process.
The operational impact of this vulnerability extends far beyond simple code execution capabilities. Local users with adb shell access can leverage this race condition to achieve system-level privileges, effectively bypassing Android's security model and gaining control over critical system functions. The ability to execute arbitrary code as the system user opens pathways for complete system compromise, including but not limited to privilege escalation, data exfiltration, and persistent backdoor installation. This vulnerability particularly affects the Android 4.4.4 operating system version and represents a fundamental flaw in how the system handles concurrent operations during package management and backup agent binding processes. The exploit demonstrates a clear violation of Android's security boundaries and highlights the importance of proper synchronization mechanisms in multi-threaded system components.
Security professionals should recognize this vulnerability as a classic example of a race condition that can be exploited to bypass access controls and achieve unauthorized privilege escalation. The vulnerability aligns with CWE-362, which specifically addresses race conditions in software systems, and represents a significant concern for any Android 4.4.4 devices that may be compromised through local access. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be categorized under T1068, which covers "Exploitation for Privilege Escalation." The exploit requires minimal user interaction beyond establishing adb shell access, making it particularly dangerous for devices that have been compromised through other attack vectors or for devices that have been improperly secured in enterprise environments where adb access should be restricted. Organizations should implement immediate mitigations including patching to newer Android versions, restricting adb shell access, and monitoring for suspicious logcat patterns that may indicate exploitation attempts. The vulnerability underscores the critical need for comprehensive security testing of concurrent operations in mobile operating systems and highlights the importance of proper synchronization mechanisms in system-level components.