CVE-2019-9446 in Android
Summary
by MITRE
In the Android kernel in the FingerTipS touchscreen driver there is a possible out of bounds write due to improper input validation. This could lead to a local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-9446 resides within the Android kernel's FingerTipS touchscreen driver component, representing a critical security flaw that could enable unauthorized privilege escalation. This issue manifests as a potential out of bounds write condition that arises from inadequate input validation mechanisms within the driver's code structure. The vulnerability specifically affects the kernel-level touchscreen driver implementation that manages input from FingerTipS touchscreen hardware devices, creating a pathway for malicious actors to exploit the system's privilege model.
The technical root cause of this vulnerability stems from improper validation of input data received from touchscreen events, which allows an attacker to craft malformed input sequences that exceed the allocated buffer boundaries. This flaw falls under the CWE-129 category of Improper Validation of Array Index, where the system fails to properly validate input parameters before using them to access array elements. The vulnerability exists in the kernel space where the touchscreen driver processes input events, making it particularly dangerous as it operates with elevated privileges typically reserved for system-level operations.
The operational impact of this vulnerability is severe, as it enables a local attacker to achieve privilege escalation from regular user context to system-level execution privileges without requiring any user interaction. This means that an attacker who has already gained access to a device with standard user privileges could potentially exploit this flaw to gain complete system control. The lack of user interaction requirement makes this vulnerability particularly concerning as it can be exploited automatically without any human intervention, potentially leading to unauthorized system compromise, data exfiltration, or persistent backdoor establishment. The exploitation process would involve crafting specific touchscreen input sequences that trigger the out of bounds write condition, allowing the attacker to overwrite critical kernel memory locations.
Mitigation strategies for CVE-2019-9446 should focus on both immediate patching and defensive measures. The primary solution involves applying the vendor-provided kernel security patches that address the input validation issues within the FingerTipS driver. Organizations should also implement kernel lockdown mechanisms and enable kernel address space layout randomization to make exploitation more difficult. Additionally, monitoring for unusual touchscreen input patterns and implementing proper input sanitization at multiple layers of the system can help detect potential exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could be categorized under T1068 for locally executed malicious code, with potential lateral movement implications once system-level access is achieved. The vulnerability demonstrates the critical importance of kernel-level input validation and the severe consequences that can arise from insufficient bounds checking in system drivers.