CVE-2020-15994: Google Chrome Use-After-Free Vulnerability

CVE-2020-15994 Overview

CVE-2020-15994 is a use after free vulnerability in the V8 JavaScript engine in Google Chrome prior to version 86.0.4240.99. This memory corruption flaw allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. Successful exploitation could enable attackers to execute arbitrary code within the context of the browser, potentially compromising user data and system integrity.

Critical Impact

Remote attackers can exploit heap corruption through malicious HTML pages, potentially achieving arbitrary code execution in the context of the user's browser session.

Affected Products

• Google Chrome prior to version 86.0.4240.99
• Google Chrome for Android
• Google Android (Chrome component)

Discovery Timeline

• 2020-11-03 - CVE-2020-15994 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-15994

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a class of memory corruption flaws that occur when a program continues to use a pointer after the memory it references has been freed. In the context of V8, Google Chrome's JavaScript engine, this type of vulnerability is particularly dangerous because V8 handles all JavaScript execution, making it a critical attack surface.

The vulnerability requires user interaction—a victim must navigate to or be redirected to a malicious webpage containing specially crafted HTML/JavaScript content. Once triggered, the heap corruption can potentially be leveraged to gain control over program execution flow, enabling remote code execution within the browser's sandboxed environment.

Root Cause

The root cause is improper memory management within the V8 JavaScript engine. When JavaScript objects are deallocated, the V8 engine failed to properly invalidate all references to the freed memory region. This allows subsequent code to access and manipulate memory that has been returned to the heap allocator, leading to heap corruption when that memory is reallocated for other purposes.

Attack Vector

The attack vector is network-based, requiring a victim to visit a malicious webpage. An attacker can exploit this vulnerability by:

1. Crafting a malicious HTML page containing JavaScript that triggers the use after free condition in V8
2. Hosting the malicious page or injecting it through compromised websites, advertisements, or phishing campaigns
3. When the victim loads the page, the JavaScript triggers the memory corruption
4. The attacker leverages the heap corruption to potentially achieve arbitrary code execution

The vulnerability exploitation mechanism involves manipulating JavaScript objects to trigger the use after free condition in V8. The crafted HTML page would contain JavaScript designed to free an object and then reference it again, causing heap corruption. For detailed technical information, refer to the Chrome Bug Report #1117258 and the Google Chrome Android Update announcement.

Detection Methods for CVE-2020-15994

Indicators of Compromise

• Unusual browser crashes or instability when visiting specific websites
• Chrome crash reports indicating V8 heap corruption or segmentation faults
• Unexpected child processes spawned by the Chrome browser
• Memory dumps showing heap corruption patterns in Chrome processes

Detection Strategies

• Monitor for Chrome versions prior to 86.0.4240.99 in asset inventory systems
• Implement browser version enforcement policies through endpoint management solutions
• Deploy network monitoring for traffic patterns associated with heap spray techniques
• Use SentinelOne Singularity to detect anomalous behavior from browser processes

Monitoring Recommendations

• Enable Chrome crash reporting and monitor for V8-related crashes
• Implement endpoint detection and response (EDR) monitoring for suspicious browser process behavior
• Monitor network traffic for connections to known malicious domains serving exploit kits
• Track browser update compliance across the organization

How to Mitigate CVE-2020-15994

Immediate Actions Required

• Update Google Chrome to version 86.0.4240.99 or later immediately
• Enable automatic Chrome updates to receive security patches promptly
• Conduct an organization-wide audit to identify systems running vulnerable Chrome versions
• Consider temporarily blocking access to untrusted websites until patches are applied

Patch Information

Google has addressed this vulnerability in Chrome version 86.0.4240.99 and later releases. The fix was included in the Chrome for Android update released on October 31, 2020. Organizations should ensure all desktop and mobile Chrome installations are updated to the patched version.

For official patch details, refer to the Google Chrome Android Update announcement.

Workarounds

• Disable JavaScript execution in Chrome as a temporary mitigation (may impact site functionality)
• Use browser isolation technologies to contain potential exploitation
• Implement network-level blocking of known malicious domains
• Enable Chrome's Site Isolation feature if not already active
• Consider using alternative browsers temporarily until Chrome is updated

# Configuration example - Force Chrome update via command line
# On Windows, check Chrome version
"C:\Program Files\Google\Chrome\Application\chrome.exe" --version

# On Linux/macOS, update Chrome package
# Debian/Ubuntu
sudo apt update && sudo apt install --only-upgrade google-chrome-stable

# macOS with Homebrew
brew upgrade --cask google-chrome