CVE-2019-9471 in Android
Summary
by MITRE
In set_outbound_iatu of abc-pcie.c, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android kernel Android ID: A-144168326
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Analysis
by VulDB Data Team • 01/07/2020
The vulnerability identified as CVE-2019-9471 resides within the Android kernel's PCIe subsystem, specifically in the set_outbound_iatu function located in the abc-pcie.c driver file. This flaw represents a critical security weakness that could enable local privilege escalation attacks, allowing an attacker with system execution privileges to gain elevated access to the system. The vulnerability manifests as a potential out-of-bounds write condition that occurs when the system fails to perform proper bounds checking on array or buffer operations. The absence of validation mechanisms in the outbound iatu (Inbound Translation Unit Address) configuration routine creates a pathway for malicious code to write data beyond the allocated memory boundaries, potentially corrupting adjacent memory regions and compromising system stability.
The technical nature of this vulnerability aligns with CWE-787, which describes out-of-bounds write conditions that occur when a program writes to memory locations outside the bounds of a buffer or array. This particular flaw is classified as a local privilege escalation vulnerability because it requires system execution privileges to exploit, but once triggered, it can elevate the attacker's privileges within the system. The attack vector does not require user interaction, making it particularly dangerous as it can be exploited automatically by malicious code running with system-level privileges. The vulnerability affects Android kernel implementations and is tracked under Android ID A-144168326, indicating its specific relevance to Android operating system security.
The operational impact of CVE-2019-9471 extends beyond simple memory corruption, as it can potentially lead to complete system compromise when exploited. An attacker who successfully exploits this vulnerability could gain elevated privileges to perform actions such as modifying system files, accessing sensitive data, or installing malicious software. The vulnerability's location within the PCIe subsystem means that it could affect hardware communication layers and potentially impact device functionality beyond simple privilege escalation. The lack of user interaction requirement makes this vulnerability particularly concerning for mobile devices where system processes may run with elevated privileges without user awareness. This flaw could enable sophisticated attacks that leverage the kernel-level access to bypass security controls and establish persistent access to the device.
Mitigation strategies for CVE-2019-9471 should focus on implementing proper bounds checking mechanisms within the affected driver code. The primary remediation involves adding comprehensive validation checks before any array or buffer operations in the set_outbound_iatu function to ensure that all write operations remain within allocated memory boundaries. System administrators and device manufacturers should prioritize applying security patches released by Android and kernel maintainers to address this vulnerability. The mitigation approach should also include monitoring for anomalous system behavior that might indicate exploitation attempts, particularly in environments where system-level processes are running with elevated privileges. Additionally, implementing runtime protections such as stack canaries, address space layout randomization, and kernel address space layout randomization could provide additional defense-in-depth measures against exploitation attempts. Organizations should also consider implementing security frameworks aligned with ATT&CK matrix concepts for kernel-level attacks, focusing on privilege escalation techniques and system modification behaviors that could indicate exploitation of this vulnerability.