CVE-2023-4431: Google Chrome Buffer Overflow Vulnerability

CVE-2023-4431 Overview

CVE-2023-4431 is an out-of-bounds memory access vulnerability in the Fonts component of Google Chrome prior to version 116.0.5845.110. This vulnerability allows a remote attacker to perform an out-of-bounds memory read by enticing a user to visit a crafted HTML page. The vulnerability was classified by Chromium as medium severity.

Critical Impact

Remote attackers can exploit this vulnerability to read sensitive information from memory or cause a denial of service condition by crafting a malicious HTML page that triggers the out-of-bounds read when processing fonts.

Affected Products

• Google Chrome versions prior to 116.0.5845.110
• Fedora Project Fedora 37, 38, and 39
• Debian Linux 10.0 and 11.0

Discovery Timeline

• 2023-08-23 - CVE CVE-2023-4431 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-4431

Vulnerability Analysis

This vulnerability (CWE-125: Out-of-bounds Read) exists in the Fonts component of Google Chrome's rendering engine. When processing specially crafted font data embedded in an HTML page, the browser fails to properly validate memory access boundaries. This allows an attacker to read memory contents beyond the intended buffer, potentially exposing sensitive information stored in adjacent memory regions.

The out-of-bounds read occurs during font parsing operations, where insufficient bounds checking allows read operations to access memory outside the allocated buffer. This type of vulnerability can lead to information disclosure if the read memory contains sensitive data, or application crashes if invalid memory addresses are accessed.

Root Cause

The root cause of CVE-2023-4431 is insufficient bounds validation in the font processing code within Google Chrome. When handling font data from web content, the Fonts component does not adequately verify that memory read operations stay within the bounds of allocated buffers. This allows crafted font data to trigger reads from unintended memory locations.

Attack Vector

The attack vector for this vulnerability is network-based and requires user interaction. An attacker must convince a victim to visit a malicious webpage containing specially crafted HTML with embedded font data designed to trigger the out-of-bounds read condition.

The exploitation scenario involves:

1. Attacker creates a malicious webpage with crafted font data
2. Victim visits the attacker-controlled page using a vulnerable version of Chrome
3. Chrome's font processing code parses the malicious font data
4. The out-of-bounds read is triggered, potentially leaking memory contents or causing a crash

The vulnerability does not require any special privileges, but user interaction in the form of navigating to the malicious page is necessary.

Detection Methods for CVE-2023-4431

Indicators of Compromise

• Unexpected browser crashes or hangs when visiting specific web pages
• Unusual memory access patterns or segmentation faults in Chrome processes
• Suspicious network requests to known malicious domains hosting crafted HTML pages
• Chrome crash reports indicating faults in font rendering subsystems

Detection Strategies

• Monitor for Chrome versions older than 116.0.5845.110 across the organization
• Implement web filtering to block access to known malicious domains exploiting browser vulnerabilities
• Deploy endpoint detection solutions capable of identifying memory corruption exploit attempts
• Review Chrome crash logs for patterns consistent with out-of-bounds memory access in font-related components

Monitoring Recommendations

• Enable Chrome's built-in crash reporting and monitor for font-related crash patterns
• Implement network monitoring to detect suspicious HTML content with unusual font data
• Configure SIEM rules to alert on multiple browser crashes from the same endpoint
• Monitor for unusual memory consumption patterns in browser processes

How to Mitigate CVE-2023-4431

Immediate Actions Required

• Update Google Chrome to version 116.0.5845.110 or later immediately
• Enable automatic Chrome updates to ensure timely patch deployment
• Apply distribution-specific security updates for Fedora and Debian systems
• Consider implementing browser isolation technologies for high-risk users

Patch Information

Google has addressed this vulnerability in Chrome version 116.0.5845.110. The fix was released as part of a stable channel update. Organizations should ensure all Chrome installations are updated to this version or later.

Additional patch resources:

• Chrome Stable Update
• Chromium Bug Report #1469348
• Debian Security Update DSA-5483
• Gentoo GLSA 202401-34

Workarounds

• Restrict browsing to trusted websites until patches can be applied
• Use browser isolation or sandboxing solutions to contain potential exploitation
• Consider temporary use of alternative browsers for high-risk activities while awaiting patch deployment
• Implement web content filtering to block potentially malicious font resources

# Configuration example
# Check current Chrome version on Linux
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