CVE-2020-6457: Google Chrome Use After Free Vulnerability

CVE-2020-6457 Overview

CVE-2020-6457 is a use-after-free vulnerability in the speech recognizer component of Google Chrome prior to version 81.0.4044.113. This memory corruption flaw allows remote attackers to potentially escape the browser sandbox through a specially crafted HTML page. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, which can lead to arbitrary code execution when an attacker can control the freed memory contents.

Critical Impact

This vulnerability enables sandbox escape, allowing attackers to break out of Chrome's security boundary and potentially execute malicious code with elevated privileges on the victim's system.

Affected Products

• Google Chrome versions prior to 81.0.4044.113
• Debian Linux 9.0
• Debian Linux 10.0

Discovery Timeline

• 2020-05-21 - CVE-2020-6457 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-6457

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a critical memory corruption issue affecting Chrome's speech recognizer functionality. The flaw exists in how the browser handles memory during speech recognition operations. When memory is deallocated but a reference to that memory location persists, subsequent use of that reference can lead to exploitation.

The sandbox escape potential makes this vulnerability particularly dangerous. Chrome's multi-process architecture relies on sandboxing to isolate the renderer process from the system. A successful sandbox escape allows an attacker to bypass these security boundaries, transitioning from executing code within a restricted renderer process to potentially gaining access to the user's system with broader privileges.

Exploitation requires user interaction—specifically, the victim must visit a malicious webpage containing crafted HTML content designed to trigger the vulnerable code path in the speech recognizer component.

Root Cause

The root cause of this vulnerability lies in improper memory management within Chrome's speech recognizer implementation. When speech recognition objects are deallocated, the browser fails to properly invalidate all references to the freed memory. This creates a dangling pointer scenario where subsequent operations can access or manipulate the freed memory region.

The speech recognizer component likely manages complex state involving callbacks and asynchronous operations. Race conditions or improper lifecycle management of these objects can result in use-after-free conditions when memory is accessed after being freed.

Attack Vector

The attack is executed over the network and requires the victim to visit a malicious webpage. An attacker would craft an HTML page that triggers the speech recognizer functionality in a specific sequence to exploit the use-after-free condition.

The attack chain typically involves:

1. A victim visits a malicious or compromised website
2. The webpage contains crafted HTML/JavaScript that invokes the speech recognizer API
3. The malicious code triggers the memory management flaw, causing a use-after-free condition
4. The attacker leverages this memory corruption to achieve code execution within the renderer process
5. The sandbox escape allows escalation beyond the browser's security boundary

Since no verified exploit code is available, the specific technical details of exploitation remain restricted. For additional technical information, refer to the Chromium Bug Report #1067851.

Detection Methods for CVE-2020-6457

Indicators of Compromise

• Unexpected crashes or instability in Chrome's speech recognition functionality
• Memory access violations or exceptions in the Chrome renderer process
• Unusual process spawning from Chrome browser processes indicating potential sandbox escape
• Anomalous network activity originating from Chrome processes to unknown external destinations

Detection Strategies

• Monitor for Chrome versions below 81.0.4044.113 across your environment using asset inventory tools
• Deploy endpoint detection rules that alert on unusual memory access patterns in browser processes
• Implement network monitoring for connections to known malicious infrastructure from browser processes
• Use SentinelOne's Behavioral AI to detect sandbox escape attempts and anomalous process behavior

Monitoring Recommendations

• Enable enhanced crash reporting to capture memory corruption events in Chrome
• Monitor system logs for evidence of exploitation attempts targeting browser components
• Track Chrome version distribution across endpoints to identify unpatched systems
• Review web traffic logs for access to domains known to host browser exploits

How to Mitigate CVE-2020-6457

Immediate Actions Required

• Update Google Chrome to version 81.0.4044.113 or later immediately
• Verify Chrome auto-update is enabled and functioning across all managed endpoints
• For Debian systems, apply updates from the Debian Security Advisory DSA-4714
• Audit systems for vulnerable Chrome versions and prioritize remediation

Patch Information

Google addressed this vulnerability in Chrome version 81.0.4044.113, released on April 15, 2020. The fix resolves the memory management issue in the speech recognizer component, preventing the use-after-free condition. For detailed release information, see the Google Chrome Update Announcement.

Debian Linux users should apply the security updates provided through DSA-4714 to ensure their systems are protected.

Workarounds

• Restrict browsing to trusted websites only until patching can be completed
• Consider disabling speech recognition functionality if not required for business operations
• Implement web filtering to block access to known malicious domains
• Use browser isolation solutions to contain potential exploitation attempts

# Verify Chrome version on Linux systems
google-chrome --version

# Check if Chrome needs updating on Debian
apt-cache policy chromium

# Apply Debian security updates
sudo apt update && sudo apt upgrade chromium