CVE-2016-10317 in Ghostscript
Summary
by MITRE
The fill_threshhold_buffer function in base/gxht_thresh.c in Artifex Software, Inc. Ghostscript 9.20 allows remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted PostScript document.
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Analysis
by VulDB Data Team • 11/27/2022
The vulnerability identified as CVE-2016-10317 represents a critical heap-based buffer overflow flaw within the Ghostscript rendering engine, specifically in the fill_threshhold_buffer function located in base/gxht_thresh.c. This issue affects Artifex Software, Inc. Ghostscript version 9.20 and demonstrates a classic memory safety vulnerability that can be exploited through malicious PostScript document manipulation. The vulnerability stems from inadequate bounds checking during the processing of threshold buffer operations, creating a condition where attacker-controlled input can exceed allocated memory boundaries and corrupt adjacent heap memory regions.
The technical exploitation of this vulnerability occurs when a malicious PostScript document is processed by Ghostscript, triggering the fill_threshhold_buffer function with crafted input parameters. The flaw manifests as a heap-based buffer overflow, where the application attempts to write data beyond the allocated buffer space, potentially leading to memory corruption that results in application crashes or more severe consequences. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which is a well-documented weakness in memory management where insufficient bounds checking allows data to overwrite adjacent memory locations. The vulnerability's impact extends beyond simple denial of service, as the heap corruption could potentially enable more sophisticated attacks depending on the execution environment and memory layout.
From an operational perspective, this vulnerability presents significant risks to organizations that process untrusted PostScript or PDF documents through Ghostscript-based applications. The remote attack vector means that adversaries can exploit this flaw without requiring local access, making it particularly dangerous in web applications, document processing services, or email filtering systems that utilize Ghostscript for rendering. The potential for unspecified other impacts suggests that beyond the immediate denial of service, attackers might be able to leverage the memory corruption for information disclosure, privilege escalation, or even remote code execution depending on the specific system configuration and memory protection mechanisms in place. This vulnerability aligns with ATT&CK technique T1203, Exploitation for Client Execution, as it enables remote code execution through crafted document processing.
Mitigation strategies for CVE-2016-10317 should prioritize immediate patching of affected Ghostscript installations to version 9.21 or later, which contains the necessary fixes for the heap buffer overflow condition. Organizations should implement strict input validation and sanitization for all PostScript and PDF documents processed through Ghostscript, particularly when handling untrusted content from external sources. Network segmentation and application whitelisting can help reduce the attack surface by limiting which systems can process potentially malicious documents. Additionally, deploying intrusion detection systems that monitor for suspicious document processing patterns and implementing robust memory protection mechanisms such as stack canaries and address space layout randomization can provide additional defense-in-depth measures. The vulnerability highlights the critical importance of regular security updates and proper input validation in document processing applications, as it demonstrates how seemingly benign rendering operations can become attack vectors when memory safety is not properly enforced.