CVE-2020-27028 in Android
Summary
by MITRE • 12/15/2020
In filter_incoming_event of hci_layer.cc, there is a possible out of bounds read due to a missing bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-141618611
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-27028 represents a critical out-of-bounds read flaw within the Bluetooth subsystem of Android 11 operating on devices with the Android ID A-141618611. This issue resides in the filter_incoming_event function located within the hci_layer.cc source file, which forms part of the Bluetooth hardware control interface layer. The vulnerability stems from the absence of proper bounds checking mechanisms when processing incoming Bluetooth events, creating a scenario where maliciously crafted data could trigger memory access violations that potentially expose sensitive system information.
The technical implementation of this vulnerability occurs within the Bluetooth host controller interface layer where incoming events from Bluetooth hardware are processed and filtered before being passed to higher-level components. When the filter_incoming_event function receives data without validating array boundaries or buffer limits, it can attempt to read memory locations beyond the allocated buffer space. This condition typically arises during the parsing of Bluetooth event packets where the code assumes a certain minimum length or structure without verifying these assumptions. The missing bounds check creates a predictable path where an attacker could manipulate input data to cause the system to access unauthorized memory regions, potentially exposing kernel memory contents or other sensitive data structures.
The operational impact of this vulnerability extends beyond simple information disclosure, as it requires only system execution privileges for exploitation, making it particularly dangerous in environments where privilege escalation is possible. An attacker with local system access could leverage this flaw to extract confidential information from the kernel memory space, potentially including cryptographic keys, user credentials, or other sensitive system data. The vulnerability's classification as a local information disclosure means that successful exploitation could provide attackers with insights into the system's internal state, potentially aiding in further attacks or privilege escalation attempts. This flaw aligns with CWE-129, which describes improper validation of array index bounds, and represents a classic example of how insufficient input validation can lead to memory safety issues.
The exploitation of this vulnerability demonstrates the importance of proper memory management practices within system-level code, particularly in security-critical components like Bluetooth stacks. Attackers could potentially craft specific Bluetooth event packets that trigger the out-of-bounds read condition, causing the system to dump memory contents that could reveal sensitive information about the device's internal operations. This type of vulnerability is particularly concerning in mobile environments where Bluetooth connectivity is frequently used and where the potential for privilege escalation exists through various attack vectors. The ATT&CK framework would categorize this as a privilege escalation technique through memory corruption, potentially leading to lateral movement or persistence within the affected system. Organizations should implement immediate mitigations including applying security patches, monitoring for suspicious Bluetooth activity patterns, and ensuring proper access controls to limit potential exploitation opportunities. The vulnerability highlights the necessity of comprehensive code reviews and static analysis tools specifically focused on memory safety in embedded systems and mobile operating environments where hardware interfaces interact with system-level processes.