CVE-2020-0465: Google Android Privilege Escalation Flaw

CVE-2020-0465 Overview

CVE-2020-0465 is an out-of-bounds write vulnerability in the Android kernel's hid-multitouch.c driver. The vulnerability exists due to a missing bounds check in various methods of the HID multitouch subsystem, which handles input from multitouch devices such as touchscreens and touchpads. This flaw could allow an attacker with physical access to the device to achieve local escalation of privilege without requiring any additional execution privileges or user interaction.

Critical Impact

This vulnerability enables local privilege escalation through physical access to an Android device. An attacker could exploit this flaw to gain elevated privileges on the system, potentially compromising sensitive data and system integrity.

Affected Products

• Google Android (kernel)
• Android devices using the vulnerable HID multitouch driver
• Upstream Linux kernel versions containing the vulnerable hid-multitouch.c code

Discovery Timeline

• 2020-12-14 - CVE-2020-0465 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-0465

Vulnerability Analysis

The vulnerability resides in the hid-multitouch.c file within the Android kernel, which is responsible for handling Human Interface Device (HID) input from multitouch devices. The flaw is classified as CWE-787 (Out-of-bounds Write), indicating that the code writes data beyond the boundaries of an allocated memory buffer.

The vulnerability requires physical access to exploit (AV:P), meaning an attacker must have direct physical access to the target device. Once physical access is obtained, exploitation is straightforward with low attack complexity, requires no privileges, and needs no user interaction. A successful exploit can lead to complete compromise of confidentiality, integrity, and availability of the affected system.

The HID multitouch driver processes input events from touch devices and translates them into system input events. When the driver fails to properly validate bounds before writing data, an attacker can craft malicious input that triggers an out-of-bounds write condition, potentially overwriting critical memory structures and achieving privilege escalation.

Root Cause

The root cause of this vulnerability is a missing bounds check in the hid-multitouch.c driver. The code fails to properly validate input data before writing to memory buffers, allowing specially crafted HID input to write beyond allocated buffer boundaries. This is a classic memory safety issue where input validation was overlooked in the device driver code path.

Attack Vector

The attack vector for CVE-2020-0465 requires physical access to the target Android device. An attacker could exploit this vulnerability by:

1. Connecting a malicious or specially crafted multitouch HID device to the target Android device
2. Sending crafted HID input data that triggers the out-of-bounds write condition
3. Leveraging the memory corruption to gain elevated privileges on the system

The vulnerability can be exploited without user interaction, meaning the attack could succeed as soon as the malicious device is connected. The attack does not require any existing privileges on the device.

Detection Methods for CVE-2020-0465

Indicators of Compromise

• Unexpected USB or HID device connections detected in system logs
• Kernel panic or system instability after connecting USB/touch input devices
• Unusual process privilege escalations following HID device attachment
• Suspicious kernel log entries related to hid-multitouch or HID input subsystem

Detection Strategies

• Monitor USB device connection events and flag unknown or unexpected HID devices
• Implement kernel auditing to detect unusual memory access patterns in HID drivers
• Deploy endpoint detection solutions capable of monitoring kernel-level activity
• Review dmesg and kernel logs for anomalies in HID multitouch processing

Monitoring Recommendations

• Enable comprehensive logging of USB device connections and disconnections
• Monitor for kernel oops or memory corruption events related to HID drivers
• Implement device whitelisting to restrict which HID devices can be connected
• Deploy SentinelOne agents to provide real-time visibility into kernel-level threats

How to Mitigate CVE-2020-0465

Immediate Actions Required

• Apply the security patches provided in the Android Security Bulletin December 2020
• Restrict physical access to Android devices in sensitive environments
• Implement USB device whitelisting to prevent unauthorized HID device connections
• Update to the latest Android kernel version that includes the fix

Patch Information

Google has addressed this vulnerability in the Android Security Bulletin December 2020. The fix adds proper bounds checking to the affected methods in hid-multitouch.c to prevent out-of-bounds write conditions. Device manufacturers and users should apply the December 2020 security patch level or later to remediate this vulnerability. The Android ID for this issue is A-162844689.

Workarounds

• Disable USB debugging and restrict USB connections when devices are unattended
• Implement USB lockdown policies to prevent unauthorized device connections
• Use device management solutions to enforce USB peripheral restrictions
• In high-security environments, consider physical port blockers for USB connections

# Configuration example
# Restrict USB HID device access on Android (requires root)
# Check current USB device permissions
adb shell ls -la /dev/input/

# Monitor HID device connections
adb shell dmesg | grep -i "hid-multitouch"

# For enterprise deployments, use MDM policies to restrict USB peripherals