CVE-2020-0018: Google Android Information Disclosure Flaw

CVE-2020-0018 Overview

CVE-2020-0018 is an information disclosure vulnerability in the Android operating system's InputDispatcher component. Specifically, the vulnerability exists in the MotionEntry::appendDescription function within InputDispatcher.cpp, where sensitive user input data may be inadvertently logged. This could allow an attacker with System execution privileges to access disclosed user input information through log files without requiring any user interaction.

Critical Impact

Local disclosure of user input data through improper logging practices, potentially exposing sensitive keyboard input and touch events to privileged attackers.

Affected Products

• Google Android 8.0
• Google Android 8.1
• Google Android 9.0
• Google Android 10.0

Discovery Timeline

• February 13, 2020 - CVE-2020-0018 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-0018

Vulnerability Analysis

This vulnerability represents a classic information leakage issue (CWE-532: Insertion of Sensitive Information into Log File) within Android's input handling subsystem. The InputDispatcher component is responsible for routing input events such as touch, keyboard, and motion events to the appropriate application windows. When the MotionEntry::appendDescription function processes motion events, it logs descriptive information that may include sensitive user input data.

The vulnerability requires local access and System-level execution privileges to exploit, as an attacker would need the ability to read system logs containing the leaked information. While this represents a significant barrier to exploitation, privileged malware or rogue system applications could potentially leverage this flaw to capture user keystrokes, touch patterns, or other sensitive input data.

Root Cause

The root cause of CVE-2020-0018 lies in improper handling of sensitive data within the logging mechanism of Android's InputDispatcher. The MotionEntry::appendDescription function in InputDispatcher.cpp writes detailed motion event information to system logs without adequately sanitizing or redacting potentially sensitive user input data. This violates the security principle of not logging sensitive information, as defined by CWE-532.

Attack Vector

Exploitation of this vulnerability requires local access to the device with System execution privileges. An attacker in this position could:

1. Execute code with System privileges on the target Android device
2. Access system log files where the InputDispatcher writes motion event descriptions
3. Parse log entries to extract sensitive user input information
4. No user interaction is required for successful exploitation

The attack is limited by the requirement for elevated privileges, meaning the attacker must already have compromised the device to some extent or have physical access with appropriate credentials.

Detection Methods for CVE-2020-0018

Indicators of Compromise

• Unusual access patterns to system log files from non-standard processes
• Unexpected processes running with System execution privileges attempting to read /dev/log/* or logcat output
• Applications requesting excessive logging permissions or accessing logs outside normal operational parameters
• Evidence of log parsing or extraction tools on the device targeting InputDispatcher entries

Detection Strategies

• Monitor for unauthorized access to Android system logs, particularly from applications that do not typically require log access
• Implement application behavior monitoring to detect processes attempting to read sensitive log data
• Deploy endpoint detection solutions capable of identifying privilege escalation attempts that could precede exploitation
• Review installed applications for unexpected System-level permissions

Monitoring Recommendations

• Enable enhanced logging and auditing for system log access attempts
• Utilize SentinelOne's behavioral AI to detect anomalous process activity associated with log file access
• Monitor for indicators of privilege escalation that could enable exploitation of this vulnerability
• Implement centralized log management to correlate suspicious access patterns across devices

How to Mitigate CVE-2020-0018

Immediate Actions Required

• Update affected Android devices to the February 2020 security patch level or later
• Review device configurations to ensure only trusted applications have System-level privileges
• Implement mobile device management (MDM) policies to enforce security updates
• Audit installed applications for unnecessary elevated permissions

Patch Information

Google addressed this vulnerability in the Android Security Bulletin February 2020. The security patch resolves the improper logging behavior in the MotionEntry::appendDescription function. Organizations should ensure all affected devices are updated to the 2020-02-01 security patch level or later.

The fix is identified by Android ID: A-139945049.

Workarounds

• Restrict applications with System execution privileges to only those that are absolutely necessary and trusted
• Implement strict application vetting processes before deploying apps with elevated permissions
• Use mobile threat defense solutions to monitor for suspicious log access behavior
• Consider disabling verbose logging on production devices where possible
• Segment sensitive operations to devices with confirmed patched status

# Verify Android security patch level
adb shell getprop ro.build.version.security_patch
# Expected output should be 2020-02-01 or later for patched devices

# Check for suspicious log access (requires root)
adb shell ps -A | grep -i log