CVE-2021-1007 in Android
Summary
by MITRE • 12/15/2021
In btu_hcif_process_event of btu_hcif.cc, there is a possible out of bounds read due to an incorrect bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-167759047
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-1007 resides within the Bluetooth subsystem of Android operating systems, specifically in the btu_hcif_process_event function located in the btu_hcif.cc source file. This issue represents a critical out-of-bounds read condition that emerges from an improper bounds check implementation. The flaw manifests when processing Bluetooth HCI (Host Controller Interface) events, which are fundamental to Bluetooth communication protocols and device management within the Android framework. Such vulnerabilities in core Bluetooth components pose significant risks as they operate at system level with elevated privileges and can potentially be exploited to access sensitive system information.
The technical implementation flaw stems from inadequate validation of buffer boundaries when handling incoming Bluetooth event data. When the system processes HCI events, it fails to properly verify the length or size of incoming data packets before attempting to read from memory locations. This incorrect bounds checking allows an attacker to craft malicious Bluetooth packets that can cause the system to read beyond allocated memory boundaries. The vulnerability specifically affects Android 12 releases and is tracked under Android ID A-167759047, indicating its severity and the need for immediate attention in the Android security update cycle. The improper validation creates a scenario where arbitrary memory locations can be accessed, potentially exposing sensitive kernel data or system information that should remain protected.
From an operational perspective, this vulnerability requires system execution privileges for exploitation but does not necessitate user interaction, making it particularly dangerous as it can be leveraged by malicious actors with local access to the device. The local information disclosure threat means that an attacker with access to the device can potentially extract confidential data from system memory, including but not limited to kernel memory contents, system configuration details, or other sensitive information that could aid in further exploitation. The implications extend beyond simple information disclosure, as such memory access could reveal patterns or data that might be used to craft more sophisticated attacks against the device or network. This vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a classic example of how buffer over-read conditions can compromise system security.
The exploitation of this vulnerability demonstrates the importance of proper input validation in system-level code, particularly within Bluetooth stack implementations that handle untrusted data from external devices. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and information disclosure techniques, where adversaries can leverage system-level flaws to gain unauthorized access to sensitive data. Mitigation strategies should include immediate deployment of Android security patches that address the bounds checking implementation in the Bluetooth subsystem. Organizations should also consider implementing network segmentation and Bluetooth device access controls to limit potential attack vectors. Additionally, regular security audits of core system components and adherence to secure coding practices, particularly around memory management and input validation, are essential to prevent similar vulnerabilities from emerging in future implementations. The vulnerability underscores the critical need for robust security testing of system-level components that operate with elevated privileges and handle external data inputs.