CVE-2020-0002: Google Android RCE Vulnerability

CVE-2020-0002 Overview

CVE-2020-0002 is a critical use-after-free vulnerability in the Android H.264 video decoder component. The vulnerability exists in the ih264d_init_decoder function within ih264d_api.c, where an out-of-bounds write condition can occur due to improper memory handling. This flaw could allow an attacker to achieve remote code execution on affected Android devices with no additional execution privileges required, though user interaction is needed for exploitation.

Critical Impact

This vulnerability enables remote code execution through malicious media content, potentially allowing complete device compromise when a user views specially crafted video content.

Affected Products

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

Discovery Timeline

• 2020-01-08 - CVE-2020-0002 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-0002

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a memory corruption issue that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of the Android H.264 decoder, the ih264d_init_decoder function in ih264d_api.c improperly handles memory operations during decoder initialization, creating conditions where freed memory can be accessed and written to.

The attack requires network access and user interaction, typically in the form of opening a malicious media file or streaming content. Once triggered, the vulnerability allows arbitrary code execution in the context of the media server process, which handles multimedia content on Android devices.

Root Cause

The root cause lies in the ih264d_init_decoder function's memory management logic within the H.264 decoder library. During decoder initialization or reinitialization, the code fails to properly track the state of allocated memory objects. When certain error conditions occur or during specific decoder state transitions, the code may free memory blocks while retaining references to them. Subsequent operations then write to these freed memory regions, corrupting heap metadata or adjacent memory structures.

Attack Vector

The attack vector is network-based, requiring an attacker to deliver malicious H.264 video content to the target device. This could be accomplished through various means:

The attacker crafts a specially malformed H.264 video file designed to trigger the use-after-free condition during decoder initialization. When a victim opens this malicious content—whether through a web browser, messaging application, or media player—the Android media framework processes the video using the vulnerable decoder. The malformed input triggers the memory corruption, allowing the attacker to execute arbitrary code. Since the media server runs with elevated privileges to access hardware resources, successful exploitation could lead to significant system compromise including data theft, surveillance, or installation of persistent malware.

Detection Methods for CVE-2020-0002

Indicators of Compromise

• Unexpected crashes or restarts of the media server process (mediaserver or media.codec)
• Unusual memory consumption patterns in media-related processes
• Suspicious H.264 video files with malformed NAL units or decoder configuration records
• Anomalous system behavior following media file playback

Detection Strategies

• Monitor for abnormal mediaserver process crashes using Android system logs
• Implement memory integrity monitoring for heap corruption indicators
• Deploy mobile threat detection solutions capable of identifying exploit attempts
• Analyze incoming media content for malformed H.264 structures at network boundaries

Monitoring Recommendations

• Enable crash reporting and centralized logging for Android device fleets
• Implement network-level inspection of media content where feasible
• Monitor for unusual process spawning or privilege escalation following media playback
• Deploy endpoint detection and response solutions on managed Android devices

How to Mitigate CVE-2020-0002

Immediate Actions Required

• Apply the January 2020 Android Security Patch immediately to all affected devices
• Restrict installation of applications from untrusted sources
• Avoid opening media files from unknown or untrusted sources
• Consider disabling automatic media playback in messaging and email applications

Patch Information

Google addressed this vulnerability in the Android Security Bulletin January 2020. The fix corrects the memory handling logic in the ih264d_init_decoder function to properly track and invalidate pointers when memory is freed. Organizations should ensure all Android devices are updated to the January 2020 security patch level or later. The vulnerability is tracked internally by Google as Android ID A-142602711.

Workarounds

• Implement mobile device management (MDM) policies to enforce timely security updates
• Use application sandboxing to limit media player access to sensitive resources
• Consider network-level filtering of media content from untrusted sources
• Deploy enterprise mobile security solutions with exploit prevention capabilities

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

# Check for mediaserver crashes in system logs
adb logcat -d | grep -i "mediaserver\|media.codec" | grep -i "crash\|fatal"