CVE-2023-4357: Google Chrome XXE Vulnerability

CVE-2023-4357 Overview

CVE-2023-4357 is an Improper Input Validation vulnerability affecting Google Chrome's XML processing component. The flaw stems from insufficient validation of untrusted input in the XML parser, which allows remote attackers to bypass file access restrictions through specially crafted HTML pages. This vulnerability enables attackers to potentially access sensitive local files that should be protected by the browser's security sandbox.

Critical Impact

Remote attackers can exploit this vulnerability to bypass Chrome's file access restrictions, potentially leading to unauthorized access to sensitive local files and data exfiltration through malicious web content.

Affected Products

• Google Chrome prior to version 116.0.5845.96
• Debian Linux 11.0 and 12.0
• Fedora 38

Discovery Timeline

• 2023-08-15 - CVE-2023-4357 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-4357

Vulnerability Analysis

This vulnerability resides in Chrome's XML processing subsystem, where insufficient validation of untrusted input allows attackers to craft malicious XML content that can bypass the browser's file access restrictions. When a user visits a malicious webpage containing specially crafted HTML and XML content, the browser's XML parser fails to properly validate the input, allowing the attacker to access local files that would normally be protected by the same-origin policy and file access controls.

The vulnerability is particularly concerning because it can be exploited remotely through a simple user action—visiting a malicious webpage. No special privileges are required on the attacker's side, and the attack can be executed with relatively low complexity. The impact includes potential compromise of confidentiality, integrity, and availability of user data.

Root Cause

The root cause of CVE-2023-4357 is the lack of proper input validation in Chrome's XML processing code (CWE-20: Improper Input Validation). The XML parser does not adequately sanitize or validate external input before processing it, creating an opportunity for attackers to inject malicious content that circumvents security controls. This allows specially crafted XML data to be processed in ways that bypass the intended file access restrictions implemented in Chrome's security model.

Attack Vector

The attack is executed remotely over the network and requires user interaction—specifically, the victim must be tricked into visiting a malicious webpage. The attacker crafts a webpage containing specially formed HTML and XML content designed to exploit the validation weakness. When the victim's Chrome browser renders this page, the vulnerable XML parser processes the malicious content without proper validation, allowing the attacker to bypass file access restrictions.

The exploitation process typically involves:

1. An attacker creating a malicious webpage with crafted HTML containing embedded XML content
2. The victim visiting the attacker-controlled webpage or being redirected to it
3. Chrome's XML parser processing the malicious content without adequate validation
4. The attacker gaining the ability to access files that should be restricted by the browser's security model

For detailed technical information about this vulnerability, refer to the Chrome Bug Report #1458911 and the Google Chrome Update Bulletin.

Detection Methods for CVE-2023-4357

Indicators of Compromise

• Unusual file access attempts originating from the Chrome browser process
• Network traffic showing suspicious XML content being loaded from untrusted external sources
• Chrome crash dumps or error logs indicating XML parsing failures
• Unexpected access to sensitive local files (e.g., credential stores, configuration files) by browser processes

Detection Strategies

• Monitor browser process behavior for anomalous file system access patterns outside normal browsing directories
• Implement network-based intrusion detection rules to identify malicious XML payloads targeting this vulnerability
• Deploy endpoint detection solutions like SentinelOne to identify and block exploitation attempts in real-time
• Analyze web proxy logs for requests containing suspicious XML structures known to be associated with this CVE

Monitoring Recommendations

• Enable Chrome's Safe Browsing feature to block known malicious pages
• Implement browser policy enforcement to restrict access to untrusted websites
• Deploy SentinelOne Singularity Platform to monitor endpoint behavior and detect file access anomalies
• Regularly review Chrome version deployments across the organization to ensure patched versions are in use

How to Mitigate CVE-2023-4357

Immediate Actions Required

• Update Google Chrome to version 116.0.5845.96 or later immediately
• Apply security updates for Debian and Fedora systems that include Chromium packages
• Implement browser policies to restrict access to untrusted web content
• Deploy endpoint protection solutions to detect and prevent exploitation attempts

Patch Information

Google has released Chrome version 116.0.5845.96 which addresses this vulnerability. The fix improves input validation in the XML processing component to prevent malicious content from bypassing file access restrictions.

Organizations should:

1. Deploy the updated Chrome version through their software management system
2. For Debian users, apply the patches detailed in Debian Security Advisory DSA-5479
3. For Fedora users, apply updates from the Fedora Package Announcements
4. For Gentoo users, refer to GLSA 202401-34 for patch information

Workarounds

• Restrict users from visiting untrusted websites through web filtering or proxy solutions
• Consider temporarily disabling or restricting XML processing features if browser updates cannot be immediately applied
• Implement network-level controls to block access to known malicious domains
• Use browser isolation technologies to contain potential exploitation attempts

# Verify Chrome version on Linux/macOS systems
google-chrome --version
# Expected output: Google Chrome 116.0.5845.96 or higher

# For enterprise deployments, verify Chrome policies are enforced
cat /etc/opt/chrome/policies/managed/*.json

# Check for automatic updates enabled
grep -r "AutoUpdateEnabled" /etc/opt/chrome/policies/