CVE-2017-13273 in Android
Summary
by MITRE
In xt_qtaguid.c, there is a race condition due to insufficient locking. This could lead to local elevation of privileges with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android kernel. Android ID: A-65853158.
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Analysis
by VulDB Data Team • 01/04/2020
The vulnerability described in CVE-2017-13273 represents a critical race condition within the Android kernel's xt_qtaguid module, which is part of the netfilter framework used for packet classification and traffic control. This flaw exists in the xt_qtaguid.c file where insufficient locking mechanisms fail to protect shared data structures during concurrent access scenarios. The race condition occurs when multiple threads or processes attempt to modify or access tagging information simultaneously without proper synchronization, creating a window where inconsistent states can be exploited. The vulnerability specifically affects Android kernel implementations and was identified through internal Android security analysis with the Android ID A-65853158.
The technical implementation of this vulnerability stems from improper mutex or spinlock handling within the xt_qtaguid module's packet tagging subsystem. When kernel threads process network packets and attempt to update tag information associated with traffic flows, the lack of adequate locking allows for simultaneous access to shared memory regions containing tagging metadata. This race condition manifests when one thread modifies a data structure while another thread reads or writes to the same location, potentially leading to memory corruption or data inconsistency. The flaw resides in the kernel's traffic control infrastructure where network packets are categorized and tagged for various purposes including bandwidth management and application-specific traffic control. This type of vulnerability maps directly to CWE-362, which describes a race condition flaw in concurrent programming where two or more threads can access shared data simultaneously, leading to unpredictable behavior and potential privilege escalation.
The operational impact of this vulnerability is severe as it enables local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. An attacker with local access to an Android device can leverage this race condition to gain elevated privileges and potentially achieve full system compromise. The exploitation process involves carefully timing concurrent operations that trigger the race condition, allowing the attacker to manipulate kernel data structures and ultimately elevate their privileges from normal user level to kernel level. This capability provides attackers with complete control over the device, enabling them to access all system resources, modify critical files, install malicious software, and potentially exfiltrate sensitive data. The vulnerability affects all Android kernel versions that implement the xt_qtaguid module, making it particularly dangerous as it could be exploited across a wide range of Android devices and versions.
Mitigation strategies for CVE-2017-13273 require immediate patching of affected Android kernel versions through official security updates provided by device manufacturers. The fix typically involves implementing proper locking mechanisms around the shared data structures in the xt_qtaguid module to prevent concurrent access during critical operations. Security researchers recommend that device manufacturers prioritize this patch deployment as it addresses a critical privilege escalation vulnerability that could be exploited by malicious applications or compromised user accounts. Additionally, system administrators should monitor for any unauthorized access patterns or anomalous network behavior that might indicate exploitation attempts. The vulnerability highlights the importance of proper kernel synchronization mechanisms and demonstrates the need for comprehensive security testing of kernel modules, particularly those handling network traffic control and packet classification. Organizations should also consider implementing additional security controls such as kernel integrity checking and monitoring for unauthorized kernel module loading to further protect against exploitation of similar vulnerabilities. This flaw serves as a reminder of the critical importance of proper concurrency control in kernel space programming and aligns with ATT&CK techniques related to privilege escalation and kernel exploitation.