CVE-2019-9447 in Android
Summary
by MITRE
In the Android kernel in the FingerTipS touchscreen driver there is a possible use-after-free due to improper locking. This could lead to a local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-9447 resides within the Android kernel's FingerTipS touchscreen driver implementation, representing a critical use-after-free condition that stems from inadequate locking mechanisms. This flaw manifests in the kernel-level touchscreen subsystem where the driver fails to properly synchronize access to shared memory resources during concurrent operations. The improper locking allows for a race condition scenario where a freed memory region can be accessed by subsequent operations before the memory is properly deallocated, creating a predictable exploitation vector for privilege escalation attacks. The vulnerability specifically affects Android devices that utilize the FingerTipS touchscreen driver, which is commonly found in various smartphone and tablet models from different manufacturers. The use-after-free condition occurs when the driver handles touchscreen input events and manages kernel memory allocations for processing touch coordinates and related data structures. When multiple threads or processes attempt to access the same memory region simultaneously without proper synchronization, the driver may free memory while another process is still referencing it, leading to undefined behavior and potential code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and unauthorized access to sensitive device functions. An attacker with local system privileges could leverage this flaw to execute arbitrary code with kernel-level privileges, effectively gaining complete control over the device's operating system. The absence of user interaction requirements makes this vulnerability particularly dangerous as it can be exploited automatically without requiring physical access or user engagement, potentially enabling remote exploitation through malicious applications or system services. The vulnerability's classification as a local privilege escalation means that an attacker who has already gained access to a user account or application context could use this flaw to elevate their privileges to system level, where they would have unrestricted access to all device resources, including encryption keys, user data, and communication channels. This represents a significant security risk in mobile environments where applications and services often require elevated privileges to function properly.
Mitigation strategies for CVE-2019-9447 should focus on both immediate patch implementation and defensive system hardening measures. Android device manufacturers and security teams should prioritize applying the kernel-level patches that address the improper locking mechanisms in the FingerTipS driver, ensuring proper synchronization primitives are implemented to prevent concurrent access to freed memory regions. The fix typically involves implementing mutex locks, spinlocks, or other synchronization mechanisms to ensure that memory operations are properly serialized and that freed resources cannot be accessed by other processes. Additionally, system administrators should consider implementing kernel module access controls and monitoring for anomalous memory access patterns that could indicate exploitation attempts. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and falls under ATT&CK technique T1068, which covers local privilege escalation through kernel exploits. Organizations should also conduct comprehensive security assessments of their Android device fleets to identify potentially affected models and ensure that all security patches are properly deployed. The remediation process requires careful testing to avoid introducing regressions in touchscreen functionality while ensuring that the underlying synchronization issues are fully resolved. Regular security updates and vulnerability scanning processes should be implemented to detect similar issues in other kernel drivers and prevent future exploitation attempts.