CVE-2021-0589 in Android
Summary
by MITRE • 07/15/2021
In BTM_TryAllocateSCN of btm_scn.cc, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-8.1 Android-9 Android-10Android ID: A-180939982
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Analysis
by VulDB Data Team • 07/18/2021
The vulnerability identified as CVE-2021-0589 represents a critical out-of-bounds write flaw within the Bluetooth management component of Android operating systems. This issue resides in the BTM_TryAllocateSCN function located in the btm_scn.cc source file, which forms part of the Bluetooth subsystem responsible for managing serial communication numbers. The vulnerability stems from an insufficient bounds check implementation that fails to properly validate array access boundaries during the allocation process. Such a flaw creates a condition where malicious code could potentially write data beyond the allocated memory buffer, leading to unpredictable behavior and system instability.
The technical exploitation of this vulnerability requires an attacker to possess user execution privileges and operate within the Android environment where Bluetooth services are active. While no user interaction is necessary for exploitation, the attacker must already have a foothold within the system to leverage this privilege escalation vector. The flaw manifests when the Bluetooth subsystem attempts to allocate serial communication numbers for device connections, specifically during the memory allocation and boundary validation process. This represents a classic buffer overflow scenario where improper input validation allows for memory corruption that can be leveraged for privilege escalation.
From a security impact perspective, this vulnerability creates a pathway for local privilege escalation from standard user privileges to elevated system-level access. The operational implications extend beyond simple system instability, as successful exploitation could enable attackers to gain root access to the device, potentially allowing them to modify system files, install malicious applications, or extract sensitive data. The vulnerability affects multiple Android versions including Android 8.1, 9, 10, and 11, indicating a widespread impact across the Android ecosystem and suggesting that the underlying code pattern has persisted through various releases. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a clear example of how improper memory management can create significant security risks in mobile operating systems.
The mitigation strategies for CVE-2021-0589 primarily involve applying the security patches released by Google as part of their regular Android security updates. System administrators and device manufacturers should prioritize the deployment of these patches across affected Android versions to prevent exploitation. Additionally, implementing runtime protections such as address space layout randomization and stack canaries can provide additional defense-in-depth measures. Organizations should also consider monitoring for suspicious Bluetooth-related activities and implementing network segmentation to limit potential attack surfaces. The vulnerability demonstrates the importance of thorough code review processes and proper bounds checking in security-critical components, particularly those handling user input or system resources in mobile operating environments where privilege escalation can have severe consequences.