CVE-2023-0933: Google Chrome PDF RCE Vulnerability

CVE-2023-0933 Overview

CVE-2023-0933 is an integer overflow vulnerability in the PDF component of Google Chrome prior to version 110.0.5481.177. This vulnerability allows a remote attacker to potentially exploit heap corruption via a crafted PDF file. When a user opens a maliciously crafted PDF document in an affected version of Chrome, the integer overflow can trigger memory corruption conditions that may lead to arbitrary code execution within the browser's context.

Critical Impact

Remote attackers can exploit this vulnerability to achieve heap corruption through specially crafted PDF files, potentially leading to arbitrary code execution when users open malicious documents.

Affected Products

• Google Chrome versions prior to 110.0.5481.177
• Chromium-based browsers using vulnerable PDF rendering components
• Desktop platforms (Windows, macOS, Linux) running affected Chrome versions

Discovery Timeline

• February 22, 2023 - CVE-2023-0933 published to NVD
• May 5, 2025 - Last updated in NVD database

Technical Details for CVE-2023-0933

Vulnerability Analysis

This vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). The flaw exists in Chrome's PDF rendering engine, which is responsible for parsing and displaying PDF documents. Integer overflow vulnerabilities occur when arithmetic operations produce a numeric value that exceeds the maximum size of the integer type used to store it, causing the value to wrap around to a much smaller or even negative number.

In this case, the integer overflow in the PDF component leads to heap corruption. When the browser allocates memory based on the overflowed calculation, it may allocate a smaller buffer than intended. Subsequent operations that write data based on the original (pre-overflow) size can then write beyond the allocated buffer boundaries, corrupting heap memory structures.

The vulnerability requires user interaction—specifically, the victim must open a maliciously crafted PDF file. This can occur through various attack vectors including phishing emails with PDF attachments, drive-by downloads from compromised websites, or social engineering tactics that convince users to open attacker-controlled documents.

Root Cause

The root cause of CVE-2023-0933 is improper handling of integer arithmetic in the PDF parsing code within Google Chrome. When processing certain PDF structures, the code performs calculations that can overflow when supplied with maliciously crafted values. This integer overflow subsequently affects memory allocation sizes, leading to undersized buffer allocations that can be exploited for heap corruption.

The vulnerability resides in how Chrome's PDFium library (the embedded PDF reader) handles specific PDF object parameters or dimensions. Integer overflows in PDF processors are particularly dangerous because PDF files contain numerous size and length fields that directly influence memory operations.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker can exploit this vulnerability through the following scenarios:

1. Email-based attacks: Sending a malicious PDF attachment that exploits the vulnerability when opened in Chrome's built-in PDF viewer
2. Web-based attacks: Hosting a malicious PDF on a website that automatically opens in Chrome when visited
3. Download-based attacks: Tricking users into downloading and opening a malicious PDF file

The vulnerability can potentially be exploited to achieve arbitrary code execution within the browser sandbox. While Chrome's sandbox provides a layer of protection, heap corruption vulnerabilities may potentially be chained with sandbox escape techniques for full system compromise.

Detection Methods for CVE-2023-0933

Indicators of Compromise

• Unusual PDF files with abnormal object sizes or dimensions that could trigger integer overflow conditions
• Chrome browser crashes when opening PDF files, particularly with heap corruption signatures
• Unexpected child processes spawned by Chrome after PDF file access
• Memory access violations or segmentation faults in Chrome's PDF rendering component

Detection Strategies

• Monitor for anomalous PDF files with extreme or unusual dimension values in object streams
• Implement endpoint detection rules that identify Chrome crashes with heap corruption patterns
• Deploy network-based inspection to detect PDF files with characteristics commonly associated with exploitation attempts
• Use behavioral analysis to identify Chrome processes exhibiting abnormal memory access patterns after PDF rendering

Monitoring Recommendations

• Enable Chrome's built-in crash reporting to identify potential exploitation attempts
• Monitor system logs for Chrome renderer process crashes, especially those occurring during PDF operations
• Implement file integrity monitoring for downloaded PDF files to detect known malicious signatures
• Configure SIEM alerts for patterns consistent with heap corruption exploitation in browser processes

How to Mitigate CVE-2023-0933

Immediate Actions Required

• Update Google Chrome to version 110.0.5481.177 or later immediately
• Enable automatic updates for Chrome to ensure timely security patch deployment
• Educate users about the risks of opening PDF files from untrusted sources
• Consider using alternative PDF readers for documents from unknown sources until all browsers are patched

Patch Information

Google has addressed this vulnerability in Chrome version 110.0.5481.177. The fix was released as part of the Stable Channel Desktop Update on February 22, 2023. Organizations should ensure all Chrome installations are updated to this version or later.

Additional patch information is available through Gentoo GLSA 202309-17 for Gentoo Linux users. The Chromium Bug Report #1404864 contains technical details about the vulnerability and its remediation.

Workarounds

• Disable Chrome's built-in PDF viewer and use an alternative PDF reader application until patching is complete
• Implement network-level filtering to scan and quarantine PDF files before they reach end users
• Configure Chrome policies to block automatic opening of PDF files, requiring explicit user download actions
• Use browser isolation technologies to render PDF content in isolated environments away from sensitive systems

# Chrome Enterprise Policy Configuration (Windows Registry)
# Disable Chrome's built-in PDF viewer as a temporary workaround
# HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome
# AlwaysOpenPdfExternally = 1

# Linux/macOS Chrome managed preferences
# Add to managed_policies.json:
# { "AlwaysOpenPdfExternally": true }