CVE-2023-3732: Google Chrome RCE Vulnerability

CVE-2023-3732 Overview

CVE-2023-3732 is an out-of-bounds memory access vulnerability in the Mojo component of Google Chrome prior to version 115.0.5790.98. This vulnerability allows a remote attacker who has already compromised the renderer process to potentially exploit heap corruption via a crafted HTML page. The flaw is classified as CWE-787 (Out-of-bounds Write), which is a memory corruption vulnerability that can lead to arbitrary code execution.

Critical Impact

A successful exploit of this vulnerability could allow attackers to execute arbitrary code within the context of the browser, potentially leading to complete system compromise, data theft, or installation of malware.

Affected Products

• Google Chrome versions prior to 115.0.5790.98
• Chromium-based browsers using vulnerable Mojo IPC components
• Linux distributions with unpatched Chromium packages (Fedora, Gentoo)

Discovery Timeline

• 2023-08-01 - CVE-2023-3732 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-3732

Vulnerability Analysis

The vulnerability exists in Chrome's Mojo inter-process communication (IPC) framework, specifically related to missing validation of IPCZ FragmentDescriptors. Mojo is a critical component that enables communication between Chrome's sandboxed processes, including the renderer, browser, and GPU processes.

When processing crafted HTML content, the vulnerable code path fails to properly validate memory boundaries when handling fragment descriptors. This allows an attacker who has already gained control of the renderer process (typically through another vulnerability or exploit chain) to corrupt heap memory in the more privileged browser process.

The vulnerability requires user interaction—specifically, the victim must navigate to a malicious webpage containing the crafted HTML. Once triggered, the out-of-bounds memory access can be leveraged to achieve heap corruption, potentially allowing the attacker to escape the renderer sandbox and execute code with higher privileges.

Root Cause

The root cause is insufficient boundary validation in the IPCZ FragmentDescriptors handling within Chrome's Mojo IPC subsystem. The code fails to properly check the bounds of memory operations when processing fragment descriptors, allowing out-of-bounds memory writes that can corrupt adjacent heap structures.

Attack Vector

The attack requires network access and user interaction. An attacker must:

1. First compromise the renderer process (typically via a separate vulnerability or exploit)
2. Craft a malicious HTML page that triggers the Mojo IPC vulnerability
3. Convince a victim to visit the malicious page

The out-of-bounds memory access in Mojo occurs when the renderer sends specially crafted IPC messages to the browser process. The missing validation in FragmentDescriptors allows the attacker to specify memory locations outside intended boundaries, enabling heap corruption. This can be chained with heap shaping techniques to achieve reliable code execution.

For detailed technical analysis of the FragmentDescriptors validation issue, see the Packet Storm Advisory.

Detection Methods for CVE-2023-3732

Indicators of Compromise

• Unusual Chrome browser crashes or instability, particularly when visiting specific websites
• Unexpected process spawning from Chrome browser processes
• Memory access violations logged in system event logs related to Chrome
• Suspicious network traffic to known malicious domains delivering exploit content

Detection Strategies

• Monitor Chrome version deployed across the environment and alert on versions prior to 115.0.5790.98
• Implement endpoint detection rules for anomalous Chrome IPC behavior patterns
• Deploy web content filtering to block known exploit delivery domains
• Use browser-based threat detection to identify malicious HTML content targeting Mojo vulnerabilities

Monitoring Recommendations

• Enable Chrome's built-in crash reporting to identify potential exploitation attempts
• Monitor for unusual parent-child process relationships originating from Chrome
• Implement network monitoring for connections to exploit kit infrastructure
• Review endpoint logs for Chrome renderer process anomalies or sandbox escape indicators

How to Mitigate CVE-2023-3732

Immediate Actions Required

• Update Google Chrome to version 115.0.5790.98 or later immediately
• Enable automatic Chrome updates across all managed endpoints
• Review and update Chromium-based browsers (Edge, Brave, Opera) to their latest patched versions
• Consider restricting access to untrusted websites until patching is complete

Patch Information

Google has released a security update addressing this vulnerability in Chrome version 115.0.5790.98. The fix addresses the missing validation in IPCZ FragmentDescriptors handling within the Mojo IPC framework.

• Google Chrome Stable Channel Update
• Chrome Bug Report
• Gentoo GLSA 202401-34
• Fedora Package Announcement

Workarounds

• Limit browsing to trusted websites only until patches can be applied
• Enable Chrome's Site Isolation feature for additional process separation
• Disable JavaScript on untrusted sites using browser extensions or enterprise policies
• Consider using alternative browsers with up-to-date security patches as a temporary measure

# Configuration example - Force Chrome update via enterprise policy
# Google Chrome Group Policy configuration
# Set AutoUpdateEnabled to true and UpdateInterval to minimum

# Linux - Check Chrome version
google-chrome --version

# Update Chrome on Debian/Ubuntu
sudo apt update && sudo apt upgrade google-chrome-stable

# Update Chrome on Fedora
sudo dnf update chromium