CVE-2017-9612 in Ghostscript GhostXPS
Summary
by MITRE
The Ins_IP function in base/ttinterp.c in Artifex Ghostscript GhostXPS 9.22 allows remote attackers to cause a denial of service (use-after-free 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-2017-9612 resides within the Ins_IP function located in base/ttinterp.c of Artifex Ghostscript GhostXPS version 9.22, representing a critical security flaw that enables remote attackers to execute arbitrary code or cause system instability. This issue manifests through a use-after-free condition that occurs when processing specially crafted XPS documents, allowing attackers to manipulate memory operations beyond their intended scope. The vulnerability specifically affects the TrueType interpreter component of Ghostscript, which is responsible for rendering font data within document processing workflows. The flaw exists because the Ins_IP function fails to properly validate memory references when handling certain font instructions, creating opportunities for attackers to exploit memory corruption patterns that can lead to application crashes or more severe consequences.
The technical exploitation of this vulnerability involves crafting malicious XPS documents that contain malformed TrueType font data, specifically targeting the Ins_IP function's handling of instruction pointers. When Ghostscript processes these documents, the function attempts to access memory locations that have already been freed or reallocated, resulting in undefined behavior patterns. This use-after-free condition falls under CWE-416, which categorizes memory access violations that occur after memory has been freed, and can potentially lead to code execution or denial of service scenarios. The attack vector requires remote delivery of malicious documents through standard document processing channels, making it particularly dangerous in environments where users routinely open documents from untrusted sources. The vulnerability demonstrates how font rendering components can serve as attack surfaces for memory corruption exploits, particularly in complex document processing applications.
The operational impact of CVE-2017-9612 extends beyond simple denial of service conditions to potentially enable more sophisticated attacks within targeted environments. Systems running GhostXPS 9.22 are vulnerable to remote exploitation without requiring user interaction beyond opening the malicious document, making it particularly dangerous in enterprise environments where document processing is common. The vulnerability can be leveraged to cause application crashes that may result in service disruption, potentially affecting document management systems, print servers, or any application that relies on Ghostscript for document rendering. In some scenarios, the memory corruption patterns could potentially be exploited to execute arbitrary code, though this requires additional conditions and is less common than the straightforward denial of service impact. The vulnerability affects systems across multiple platforms where Ghostscript is deployed, including Windows, Linux, and Unix-based systems, making it a widespread concern for organizations relying on document processing infrastructure.
Organizations should implement immediate mitigations to address this vulnerability by upgrading to Ghostscript versions that contain the patched Ins_IP function implementation, specifically versions 9.23 and later. The patch addresses the memory management issues by ensuring proper validation of instruction pointer references and implementing additional bounds checking mechanisms within the TrueType interpreter. System administrators should also consider implementing document filtering mechanisms that can detect and block potentially malicious XPS documents before they reach the processing engine, particularly in environments where document uploads are permitted. Network-level protections should include implementing sandboxed document processing environments where vulnerable applications operate in isolated execution contexts, preventing potential code execution from affecting core system resources. Additionally, regular security assessments should verify that all document processing components are updated to mitigate similar vulnerabilities, as the use-after-free pattern is a common attack vector in document processing software that requires ongoing vigilance and patch management practices to prevent exploitation.