CVE-2017-9610 in Ghostscript GhostXPS
Summary
by MITRE
The xps_load_sfnt_name function in xps/xpsfont.c in Artifex Ghostscript GhostXPS 9.22 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) or possibly have unspecified other impact via a crafted document.
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Analysis
by VulDB Data Team • 12/14/2022
The vulnerability identified as CVE-2017-9610 resides within the GhostXPS component of Artifex Ghostscript version 9.22, specifically in the xps_load_sfnt_name function located in xps/xpsfont.c. This flaw represents a heap-based buffer over-read condition that can be exploited by remote attackers through the careful crafting of XPS documents. The vulnerability manifests when the application processes font data within XPS documents, particularly when handling sfnt (scalable font) name tables that contain malformed or excessively large data structures. The flaw stems from inadequate input validation and bounds checking within the font processing pipeline, where the application fails to properly verify the size and structure of font name data before attempting to read from memory locations.
The technical execution of this vulnerability involves attackers constructing malicious XPS documents containing specially formatted font data that triggers the buffer over-read condition during the xps_load_sfnt_name function execution. When Ghostscript attempts to parse the crafted font name table entries, it reads beyond the allocated memory boundaries, potentially accessing invalid memory locations or corrupting adjacent heap data. This over-read behavior can result in application crashes due to segmentation faults or access violations, effectively causing a denial of service condition. The vulnerability's impact extends beyond simple service disruption, as the memory corruption patterns may potentially enable more sophisticated attacks depending on the execution environment and memory layout. The flaw demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read vulnerabilities, and may also relate to CWE-787, representing out-of-bounds write conditions that can occur as secondary effects of buffer over-reads.
The operational impact of CVE-2017-9610 presents significant risks for organizations relying on Ghostscript for document processing and rendering, particularly in environments where XPS document handling is common. Attackers can leverage this vulnerability to disrupt document processing workflows, potentially affecting print servers, document conversion services, or any system that processes XPS documents through Ghostscript. The remote exploitability means that systems processing untrusted XPS documents from web services, email attachments, or file sharing platforms could be compromised without user interaction, making this a particularly concerning vulnerability for enterprise environments. The unspecified other impacts mentioned in the vulnerability description suggest potential for more severe consequences including information disclosure or privilege escalation, though these remain unproven and would depend on specific system configurations and memory layouts. Organizations using Ghostscript in production environments face potential business disruption and security risks, as this vulnerability can be exploited without requiring user interaction or specialized knowledge of the target system.
Mitigation strategies for CVE-2017-9610 should prioritize immediate patching of affected Ghostscript installations to version 9.23 or later, which contains the necessary fixes for the buffer over-read condition. System administrators should implement strict document validation policies for XPS files, particularly when processing documents from untrusted sources, and consider deploying sandboxed environments for document processing to limit potential impact if exploitation occurs. Network-level controls such as content filtering and document validation gateways can provide additional defense-in-depth measures, while monitoring systems should be configured to detect unusual application crashes or memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing principle of least privilege for Ghostscript processes, limiting their access to system resources and preventing potential escalation attacks. The vulnerability highlights the importance of regular security updates and proper input validation in document processing systems, aligning with ATT&CK technique T1203 for legitimate credentials and T1059 for command and scripting interfaces, as exploitation may involve attempting to bypass security controls through crafted document processing. Additionally, this vulnerability underscores the necessity of comprehensive security testing for font processing libraries and document parsing components, particularly in systems handling untrusted document formats.