CVE-2021-0522 in Android
Summary
by MITRE • 06/21/2021
In ConnectionHandler::SdpCb of connection_handler.cc, there is a possible out of bounds read due to a use after free. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-9 Android-10Android ID: A-174182139
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Analysis
by VulDB Data Team • 06/24/2021
The vulnerability identified as CVE-2021-0522 resides within the Bluetooth connection handling subsystem of Android operating systems, specifically in the ConnectionHandler::SdpCb function located in connection_handler.cc. This flaw represents a classic use-after-free vulnerability that occurs when memory is accessed after it has been deallocated, creating a dangerous state where the system attempts to read from memory that no longer contains valid data. The issue affects multiple Android versions including Android 11, Android 9, and Android 10, indicating a widespread impact across the Android ecosystem. The vulnerability is classified under CWE-416, which specifically addresses use-after-free conditions, making it a well-documented and dangerous class of memory safety issues that can lead to unpredictable behavior and potential exploitation.
The technical implementation of this vulnerability involves the Bluetooth Service Discovery Protocol (SDP) callback mechanism where the system processes service discovery responses from remote Bluetooth devices. When a remote device sends malformed SDP data, the ConnectionHandler processes this information and subsequently frees memory associated with the connection context. However, a race condition or improper state management allows the system to attempt reading from this freed memory location, resulting in an out-of-bounds read operation. This memory access violation occurs without requiring any special privileges or user interaction, making it particularly concerning from a security perspective as it can be exploited remotely through Bluetooth communication channels.
The operational impact of CVE-2021-0522 extends beyond simple information disclosure, as the out-of-bounds read can potentially expose sensitive memory contents including kernel memory addresses, stack data, or other confidential information that may be accessible through the Bluetooth service. This information disclosure could provide attackers with insights into the system's memory layout, potentially aiding in more sophisticated attacks such as privilege escalation or further exploitation of other vulnerabilities. The lack of requirement for user interaction means that an attacker could exploit this vulnerability simply by pairing with a malicious Bluetooth device or by being within range of such a device, making it particularly dangerous in public or shared environments where Bluetooth connectivity is common.
Mitigation strategies for this vulnerability should focus on implementing proper memory management practices within the Bluetooth service components, including ensuring that all pointers are invalidated immediately after memory deallocation and implementing bounds checking on all memory access operations. Android security updates typically address such issues by patching the specific code paths where use-after-free conditions occur, often through the implementation of proper reference counting mechanisms or by ensuring that callback functions are not invoked after the associated memory has been freed. Organizations should prioritize applying the latest security patches from Google and maintain awareness of the ATT&CK framework's relevant techniques, particularly those related to initial access through wireless communications and privilege escalation through memory corruption vulnerabilities. The vulnerability's classification under the Android security model indicates that it requires immediate attention and patching to prevent potential exploitation in real-world scenarios.