CVE-2024-8639: Google Chrome Use After Free Vulnerability

CVE-2024-8639 Overview

CVE-2024-8639 is a use after free vulnerability in the Autofill component of Google Chrome on Android. This memory corruption flaw exists in versions prior to 128.0.6613.137 and allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. The vulnerability has been classified as High severity by the Chromium security team.

Critical Impact

Remote attackers can potentially achieve code execution through heap corruption by exploiting this use after free condition in Chrome's Autofill functionality on Android devices.

Affected Products

• Google Chrome versions prior to 128.0.6613.137
• Google Chrome on Android platform
• All Android devices running vulnerable Chrome versions

Discovery Timeline

• 2024-09-11 - CVE-2024-8639 published to NVD
• 2024-09-13 - Last updated in NVD database

Technical Details for CVE-2024-8639

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a memory corruption issue that occurs when a program continues to reference memory after it has been freed. In the context of Chrome's Autofill feature on Android, the vulnerability exists within the component responsible for automatically filling form fields with saved user data.

The attack requires user interaction, specifically that a victim navigate to a malicious webpage containing specially crafted HTML content. Upon triggering the vulnerable code path in the Autofill component, the attacker can corrupt the heap memory, potentially leading to arbitrary code execution within the Chrome browser process.

The vulnerability is accessible remotely over the network and does not require any special privileges or authentication to exploit. However, user interaction is necessary to trigger the vulnerability, as the victim must actively visit the attacker-controlled page.

Root Cause

The root cause stems from improper memory management in Chrome's Autofill component on Android. A use after free condition occurs when the code references a memory object that has already been deallocated. This typically happens due to incorrect object lifecycle management, where pointers to freed memory are not properly nullified or when asynchronous operations access memory that has been released by another part of the code.

Attack Vector

The attack vector is network-based, where an attacker hosts a malicious webpage containing specially crafted HTML designed to trigger the use after free condition in Chrome's Autofill functionality. When a victim using a vulnerable version of Chrome on Android visits this page, the malicious HTML can trigger the vulnerability, potentially allowing heap corruption and subsequent code execution.

The attack scenario typically involves:

1. Attacker crafts a malicious HTML page designed to trigger the Autofill use after free condition
2. Victim is lured to visit the attacker-controlled webpage on their Android device using Chrome
3. The malicious page triggers the vulnerability during Autofill operations
4. Heap corruption occurs, potentially allowing arbitrary code execution in the context of the Chrome browser

Detection Methods for CVE-2024-8639

Indicators of Compromise

• Unexpected Chrome browser crashes on Android devices, particularly when interacting with form fields
• Abnormal memory consumption patterns in the Chrome browser process
• Detection of malicious HTML pages designed to exploit Autofill functionality
• Anomalous network traffic to known malicious domains hosting exploit code

Detection Strategies

• Monitor browser crash reports for patterns indicating heap corruption in Autofill-related code paths
• Implement network-level detection for known malicious payloads targeting Chrome Autofill
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts
• Analyze web traffic for suspicious HTML content patterns associated with use after free exploits

Monitoring Recommendations

• Enable Chrome crash reporting and analyze crash dumps for exploitation indicators
• Monitor for unusual Chrome process behavior on Android devices across the organization
• Implement URL filtering to block access to known malicious domains
• Configure mobile device management (MDM) solutions to track Chrome version compliance

How to Mitigate CVE-2024-8639

Immediate Actions Required

• Update Google Chrome on Android to version 128.0.6613.137 or later immediately
• Verify Chrome auto-update is enabled on all managed Android devices
• Consider temporarily disabling Autofill functionality if immediate patching is not possible
• Educate users about the risks of visiting untrusted websites until patches are applied

Patch Information

Google has released a security update addressing this vulnerability in Chrome version 128.0.6613.137. Organizations should prioritize updating all Chrome installations on Android devices to this version or later. The patch was announced via the Google Chrome Update Announcement.

Additional technical details can be found in the Chromium Issue Tracker Entry.

Workarounds

• Disable Chrome Autofill functionality in Settings > Passwords and autofill until the update is applied
• Use an alternative browser temporarily if Chrome cannot be immediately updated
• Implement strict URL filtering to prevent access to potentially malicious websites
• Enable Chrome's Safe Browsing feature for enhanced protection against malicious sites

# Verify Chrome version on Android via ADB
adb shell dumpsys package com.android.chrome | grep versionName
# Expected output should show version 128.0.6613.137 or higher