CVE-2021-0652: Android Privilege Escalation Vulnerability

CVE-2021-0652 Overview

CVE-2021-0652 is a race condition vulnerability affecting Google Android's VectorDrawable component. The flaw exists in VectorDrawable::VectorDrawable of VectorDrawable.java, where memory corruption can occur due to the sharing of objects that are not thread-safe. This vulnerability enables local privilege escalation without requiring additional execution privileges or user interaction.

Critical Impact

Successful exploitation allows an attacker to escalate privileges locally on affected Android devices, potentially gaining elevated system access without user interaction.

Affected Products

• Google Android 8.1
• Google Android 9.0
• Google Android 10.0
• Google Android 11.0

Discovery Timeline

• 2021-10-22 - CVE-2021-0652 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-0652

Vulnerability Analysis

This vulnerability stems from a race condition (CWE-362) in the Android graphics framework, specifically within the VectorDrawable class implementation. The flaw allows for memory corruption when non-thread-safe objects are shared between concurrent execution contexts.

The vulnerability requires local access to exploit but does not need any special privileges or user interaction, making it particularly dangerous for scenarios where malicious applications are installed on target devices. An attacker could leverage this flaw to corrupt memory in a controlled manner, ultimately achieving privilege escalation on the affected Android system.

Root Cause

The root cause of this vulnerability lies in improper thread synchronization within the VectorDrawable.java implementation. When VectorDrawable objects are accessed concurrently without proper thread-safety mechanisms, the shared state can become corrupted. This race condition occurs because the code assumes single-threaded access to internal data structures that may actually be accessed from multiple threads simultaneously.

Attack Vector

The attack vector for CVE-2021-0652 is local, meaning an attacker would need code execution on the target device to exploit this vulnerability. This is typically achieved through a malicious application installed on the Android device.

The exploitation process involves triggering concurrent access to VectorDrawable objects, inducing the race condition that leads to memory corruption. The attacker can then leverage this corrupted memory state to escalate privileges on the device. No user interaction is required once the malicious code is present on the device, and no additional execution privileges are needed to trigger the vulnerability.

Detection Methods for CVE-2021-0652

Indicators of Compromise

• Unusual application crashes or system instability related to graphics rendering
• Unexpected privilege escalation attempts from installed applications
• Abnormal memory access patterns in the Android graphics framework
• Applications attempting to manipulate VectorDrawable objects in suspicious multi-threaded contexts

Detection Strategies

• Monitor for unusual crash reports originating from VectorDrawable.java or related graphics components
• Implement behavioral analysis to detect applications exhibiting race condition exploitation patterns
• Deploy endpoint detection solutions capable of identifying privilege escalation attempts on Android devices
• Review installed applications for suspicious threading behavior targeting graphics components

Monitoring Recommendations

• Enable comprehensive logging for Android system services and graphics framework
• Monitor for unexpected system calls or privilege changes from user-space applications
• Implement runtime application self-protection (RASP) to detect memory corruption attempts
• Deploy mobile threat defense solutions to identify potentially malicious applications

How to Mitigate CVE-2021-0652

Immediate Actions Required

• Update all affected Android devices to the latest security patch level
• Review and remove any untrusted applications from affected devices
• Enable Google Play Protect to scan for potentially harmful applications
• Consider implementing mobile device management (MDM) solutions to enforce security policies

Patch Information

Google addressed this vulnerability in the Android Security Bulletin October 2021. The security update is identified by Android ID A-185178568. Device manufacturers and carriers should ensure these patches are distributed to end users. Users should verify their devices are running security patch levels from October 2021 or later.

Workarounds

• Restrict installation of applications to trusted sources only (Google Play Store)
• Implement application whitelisting on managed devices
• Use mobile threat defense solutions to detect and block exploitation attempts
• Consider network segmentation to limit lateral movement if a device is compromised