CVE-2021-1022 in Android
Summary
by MITRE • 12/15/2021
In btif_in_hf_client_generic_evt of btif_hf_client.cc, there is a possible Bluetooth service crash due to a missing null check. This could lead to remote denial of service with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-180420059
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-1022 resides within the Bluetooth HID (Human Interface Device) client implementation of Android 12 systems, specifically within the btif_hf_client.cc source file. This flaw manifests in the btif_in_hf_client_generic_evt function where a critical null pointer check is absent, creating a potential crash scenario that can be exploited remotely without requiring any special privileges or user interaction. The vulnerability represents a significant security concern as it allows for remote denial of service attacks against Bluetooth services, effectively disrupting the normal operation of Bluetooth connectivity features on affected devices. The issue stems from inadequate input validation within the Bluetooth stack's client-side processing logic, where the system fails to properly validate pointer references before attempting to dereference them.
The technical nature of this vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations. This weakness allows attackers to cause system instability by manipulating Bluetooth service communications to trigger the missing null check scenario. The operational impact extends beyond simple service disruption as it can affect the entire Bluetooth subsystem, potentially rendering devices unable to establish or maintain Bluetooth connections. The vulnerability exists at the application layer of the Bluetooth protocol stack, specifically within the Hands-Free profile client implementation that handles Bluetooth audio and communication services. Attackers can exploit this by sending specially crafted Bluetooth packets to a target device, causing the Bluetooth service to crash and restart, thereby creating a denial of service condition that can be repeated indefinitely.
From an attacker perspective, this vulnerability provides a straightforward path to service disruption without requiring any authentication or elevated privileges, making it particularly dangerous in environments where Bluetooth connectivity is critical. The lack of user interaction requirements means that exploitation can occur passively, potentially allowing for automated attack campaigns against multiple devices within range. The vulnerability affects the Android 12 operating system specifically, indicating that it was introduced in the Bluetooth stack implementation during the development cycle leading up to that version. The Android ID A-180420059 indicates that this issue was properly tracked and documented within Google's internal security tracking systems, confirming its recognition as a legitimate security concern that required mitigation.
Mitigation strategies for this vulnerability primarily involve applying the official Android security patches released by Google, which include the necessary null pointer checks to prevent the crash condition. System administrators and device manufacturers should prioritize deployment of these updates across all affected Android 12 devices to prevent exploitation. Additionally, network monitoring solutions should be configured to detect anomalous Bluetooth traffic patterns that might indicate exploitation attempts, though this approach provides reactive rather than preventive protection. The vulnerability demonstrates the importance of thorough input validation in networked service implementations and highlights the need for comprehensive testing of Bluetooth stack components to prevent similar issues in future releases. Organizations should also consider implementing network segmentation and access controls to limit potential exploitation vectors, particularly in enterprise environments where Bluetooth connectivity may be exposed to untrusted networks or devices.