CVE-2024-33871: Artifex Ghostscript RCE Vulnerability

CVE-2024-33871 Overview

CVE-2024-33871 is an arbitrary code execution vulnerability discovered in Artifex Ghostscript before version 10.03.1. The vulnerability exists in the contrib/opvp/gdevopvp.c file, where the handling of custom Driver libraries allows attackers to execute arbitrary code via specially crafted PostScript documents. This occurs because the Driver parameter for opvp (and oprp) devices can specify an arbitrary name for a dynamic library, which is then loaded without proper validation.

Critical Impact

Attackers can achieve arbitrary code execution on systems processing malicious PostScript documents, potentially leading to complete system compromise, data theft, or lateral movement within affected networks.

Affected Products

• Artifex Ghostscript versions prior to 10.03.1
• Systems using opvp or oprp device drivers
• Applications and services that process PostScript documents using vulnerable Ghostscript versions

Discovery Timeline

• 2024-07-03 - CVE-2024-33871 published to NVD
• 2025-04-16 - Last updated in NVD database

Technical Details for CVE-2024-33871

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code / Code Injection). The flaw resides in how Ghostscript handles the Driver parameter for opvp and oprp devices within the gdevopvp.c source file. When processing PostScript documents, Ghostscript allows specification of a custom driver library through the Driver parameter. The application fails to validate or restrict the library names that can be specified, enabling attackers to load arbitrary dynamic libraries.

The attack requires user interaction, typically achieved by convincing a target to open a malicious PostScript document. Once opened, the crafted document can instruct Ghostscript to load an attacker-controlled library, resulting in arbitrary code execution with the privileges of the Ghostscript process.

Root Cause

The root cause stems from insufficient input validation in the opvp/oprp device driver implementation. The gdevopvp.c file accepts driver library names without proper sanitization or allowlisting, allowing arbitrary paths to be specified for dynamic library loading. This design flaw enables malicious PostScript documents to reference and load external libraries from attacker-controlled locations.

Attack Vector

The attack is network-accessible, requiring an attacker to deliver a malicious PostScript document to a victim. Common attack vectors include:

• Email attachments containing crafted PostScript or PDF files
• Web-based document preview services processing uploaded files
• Print servers and document processing pipelines
• Any application using Ghostscript for document rendering

When the victim opens or processes the malicious document, Ghostscript parses the embedded instructions, including the malicious Driver parameter that points to an attacker's library. The library is then dynamically loaded and executed, granting the attacker code execution capabilities.

Detection Methods for CVE-2024-33871

Indicators of Compromise

• Unusual dynamic library loading by Ghostscript processes (gs or related binaries)
• PostScript documents containing suspicious Driver parameter specifications pointing to non-standard paths
• Unexpected network connections originating from document processing services
• New or modified library files in temporary directories or user-writable locations

Detection Strategies

• Monitor for gs or Ghostscript-related processes attempting to load libraries from unexpected locations
• Implement file integrity monitoring on systems running Ghostscript to detect unauthorized library additions
• Review logs for PostScript processing errors or anomalies that may indicate exploitation attempts
• Deploy endpoint detection solutions capable of identifying code injection attempts through document processing

Monitoring Recommendations

• Enable enhanced logging for document processing services and Ghostscript operations
• Monitor process creation events for child processes spawned by Ghostscript with unusual parameters
• Implement network monitoring for unexpected outbound connections from document processing systems
• Set up alerts for any attempts to load dynamic libraries from user-writable directories

How to Mitigate CVE-2024-33871

Immediate Actions Required

• Upgrade Artifex Ghostscript to version 10.03.1 or later immediately
• Restrict processing of untrusted PostScript documents until patching is complete
• Consider implementing -dSAFER mode for Ghostscript operations as an additional security layer
• Audit systems for any signs of compromise if untrusted documents have been processed

Patch Information

Artifex has released a security patch addressing this vulnerability. The fix is included in Ghostscript version 10.03.1 and is available through the official Ghostscript commit 7145885041bb. Organizations should update to the latest stable release from Artifex. Additional technical details can be found in the Ghostscript Bug Report #707754 and the Openwall OSS-Security Discussion.

Workarounds

• Run Ghostscript with -dSAFER flag to restrict file operations and disable dangerous features
• Implement strict input validation and sandboxing for document processing pipelines
• Disable or remove opvp and oprp device drivers if not required for operations
• Process untrusted documents in isolated environments with limited system access

# Run Ghostscript with SAFER mode enabled
gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input.ps

# Restrict device access by specifying permitted devices only
gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -dPDFSETTINGS=/safe input.ps