CVE-2018-10194 in Ghostscript
Summary
by MITRE
The set_text_distance function in devices/vector/gdevpdts.c in the pdfwrite component in Artifex Ghostscript through 9.22 does not prevent overflows in text-positioning calculation, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted PDF document.
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Analysis
by VulDB Data Team • 02/28/2023
The vulnerability identified as CVE-2018-10194 resides within the pdfwrite component of Artifex Ghostscript version 9.22 and earlier, specifically affecting the set_text_distance function located in devices/vector/gdevpdts.c. This flaw represents a classic buffer overflow condition that occurs during text-positioning calculations when processing specially crafted PDF documents. The vulnerability stems from insufficient input validation and boundary checking mechanisms within the text handling routines of the pdfwrite device driver, which is responsible for converting PDF content into vector graphics formats. Attackers can exploit this weakness by crafting malicious PDF files that trigger integer overflows during text positioning operations, leading to memory corruption and system instability.
The technical implementation of this vulnerability involves the manipulation of text positioning parameters within PDF documents, where the set_text_distance function fails to properly validate the range of calculated text distances before using them in subsequent memory operations. When processing malformed PDF content, the function performs arithmetic operations on text positioning values that can exceed the maximum representable integer values, causing overflow conditions that result in unpredictable memory access patterns. This type of vulnerability falls under CWE-190, Integer Overflow or Wraparound, and specifically relates to CWE-787, Out-of-bounds Write, as the overflow conditions can lead to memory corruption that affects program execution flow and potentially enables arbitrary code execution. The vulnerability operates at the intersection of multiple ATT&CK techniques including T1059.007, Command and Scripting Interpreter: PowerShell, and T1499.004, Network Denial of Service, depending on the exploitation vector and target system configuration.
The operational impact of CVE-2018-10194 manifests primarily as denial of service conditions that can crash the Ghostscript application when processing malicious PDF documents. In some scenarios, the overflow conditions may allow for more severe consequences including arbitrary code execution, though the primary reported impact remains system instability and application termination. The vulnerability affects systems that process PDF documents through Ghostscript's pdfwrite component, including servers, workstations, and applications that utilize Ghostscript for PDF rendering and conversion. Attackers can leverage this vulnerability in various attack scenarios including email-based payload delivery, web-based exploitation, and file sharing platforms where PDF documents are commonly processed. The exploitability of this vulnerability is enhanced by the fact that Ghostscript is widely deployed across enterprise environments, making it an attractive target for adversaries seeking to disrupt document processing services or gain unauthorized access to systems.
Mitigation strategies for CVE-2018-10194 focus on both immediate remediation and long-term architectural improvements. The primary solution involves upgrading to Ghostscript version 9.23 or later, where the vulnerability has been patched through enhanced input validation and proper integer overflow handling in the set_text_distance function. Organizations should implement comprehensive patch management procedures to ensure all systems utilizing Ghostscript components receive the necessary updates promptly. Additional protective measures include implementing strict PDF document validation and sanitization processes before processing, deploying sandboxing mechanisms for PDF handling, and configuring network access controls to limit exposure to potentially malicious PDF content. Security monitoring should include detection of unusual Ghostscript process behavior, memory access patterns, and application crash events that may indicate exploitation attempts. The vulnerability highlights the importance of input validation and robust error handling in graphics processing libraries, particularly those handling untrusted content from external sources. Organizations should also consider implementing automated vulnerability scanning and penetration testing procedures to identify similar weaknesses in their document processing infrastructure and ensure compliance with security standards such as those outlined in NIST SP 800-53 and ISO 27001 frameworks.