CVE-2024-29509: Artifex Ghostscript Buffer Overflow Flaw

CVE-2024-29509 Overview

CVE-2024-29509 is a heap-based buffer overflow vulnerability affecting Artifex Ghostscript versions prior to 10.03.0. The vulnerability occurs when processing PDFPassword parameters (such as those used with runpdf) that contain a null byte (\000) in the middle of the string. This improper handling of embedded null bytes can lead to memory corruption, potentially enabling remote code execution.

Critical Impact

Successful exploitation could allow attackers to execute arbitrary code on affected systems by crafting malicious PDF files with specially constructed password parameters, compromising system confidentiality, integrity, and availability.

Affected Products

• Artifex Ghostscript versions prior to 10.03.0
• Systems using Ghostscript for PDF processing with password-protected documents
• Applications and services that rely on Ghostscript for document conversion

Discovery Timeline

• 2024-07-03 - CVE-2024-29509 published to NVD
• 2025-03-20 - Last updated in NVD database

Technical Details for CVE-2024-29509

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), specifically manifesting as a heap-based buffer overflow in Ghostscript's PDF password handling routines. The flaw occurs when processing PDFPassword values that contain embedded null bytes (\000) within the string.

When Ghostscript processes a PDF file that requires authentication, the PDFPassword parameter is passed to internal functions. The vulnerability arises because the code fails to properly account for null bytes appearing in the middle of the password string, leading to incorrect length calculations and subsequent heap memory corruption.

The attack requires user interaction, as a victim must open or process a maliciously crafted PDF document. However, the network attack vector indicates this could be exploited through email attachments, web downloads, or automated document processing pipelines. No privileges are required to exploit this vulnerability.

Root Cause

The root cause of this vulnerability lies in improper string handling when processing PDFPassword parameters. C-style string functions typically treat null bytes as string terminators. When a password contains an embedded null byte, the code may incorrectly calculate the string length, leading to a mismatch between the allocated buffer size and the actual data being written. This discrepancy results in a heap-based buffer overflow, allowing attackers to corrupt adjacent heap memory structures.

Attack Vector

The attack vector for CVE-2024-29509 involves crafting a malicious PDF document that triggers the vulnerable code path. An attacker would create a PDF file requiring a password, with the password parameter containing strategically placed null bytes. When a victim processes this document using an affected version of Ghostscript, the heap overflow occurs.

Common exploitation scenarios include:

• Malicious PDF attachments sent via email
• Compromised or malicious websites serving crafted PDF files
• Automated document processing systems that convert or render PDFs
• Print spooler services using Ghostscript for PDF rendering

The vulnerability can be exploited without authentication, making it particularly dangerous in environments where Ghostscript processes untrusted documents automatically.

Detection Methods for CVE-2024-29509

Indicators of Compromise

• Unexpected crashes or segmentation faults in Ghostscript processes when handling PDF files
• Anomalous memory consumption patterns in gs or related Ghostscript executables
• PDF files with unusual or malformed password metadata structures
• Core dumps indicating heap corruption in Ghostscript libraries

Detection Strategies

• Monitor for Ghostscript process crashes that indicate heap corruption or segmentation faults
• Implement file integrity monitoring on systems running Ghostscript to detect unauthorized modifications
• Deploy endpoint detection rules targeting suspicious PDF file characteristics with embedded null bytes in metadata
• Review application logs for repeated Ghostscript failures on specific documents

Monitoring Recommendations

• Enable detailed logging for document processing pipelines that use Ghostscript
• Implement alerting for abnormal Ghostscript process behavior including unexpected terminations
• Monitor network traffic for PDF files being downloaded from untrusted sources
• Audit systems for Ghostscript versions prior to 10.03.0 using software inventory tools

How to Mitigate CVE-2024-29509

Immediate Actions Required

• Upgrade Artifex Ghostscript to version 10.03.0 or later immediately
• Audit all systems and applications that depend on Ghostscript for PDF processing
• Implement input validation on document processing pipelines to reject potentially malicious PDFs
• Consider isolating Ghostscript execution in sandboxed environments until patching is complete

Patch Information

Artifex has addressed this vulnerability in Ghostscript version 10.03.0. The fix is available through the official Ghostscript Git repository, with the relevant commit identified as 917b3a71. Organizations should update to the patched version through their package managers or by compiling from source.

Additional technical details are available in the Ghostscript Bug Report #707510 and the Openwall OSS Security Discussion.

Workarounds

• Disable PDF password processing functionality if not required for business operations
• Implement network-level filtering to scan and quarantine suspicious PDF files before they reach Ghostscript
• Run Ghostscript processes with reduced privileges and in isolated containers or sandboxes
• Configure application firewalls to block PDF uploads from untrusted sources until patching is complete

# Configuration example - Check Ghostscript version and update
# Verify current Ghostscript version
gs --version

# For Debian/Ubuntu systems, update to patched version
sudo apt update && sudo apt install ghostscript

# For RHEL/CentOS systems
sudo yum update ghostscript

# Verify the updated version is 10.03.0 or later
gs --version