CVE-2018-16585 in Ghostscript
Summary
by MITRE
An issue was discovered in Artifex Ghostscript before 9.24. The .setdistillerkeys PostScript command is accepted even though it is not intended for use during document processing (e.g., after the startup phase). This leads to memory corruption, allowing remote attackers able to supply crafted PostScript to crash the interpreter or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-16585 represents a critical memory corruption flaw within the Artifex Ghostscript PDF rendering engine affecting versions prior to 9.24. This issue stems from improper validation of the .setdistillerkeys PostScript command which should normally be restricted to the initial startup phase of document processing. The flaw allows malicious actors to inject this command during active document processing, bypassing intended security boundaries and creating opportunities for arbitrary code execution or system instability.
The technical implementation of this vulnerability resides in the PostScript interpreter's command validation mechanism where the .setdistillerkeys command is not properly constrained to its intended execution context. This command is designed to configure internal distiller parameters during the initialization phase, but the lack of proper context validation permits its execution at inappropriate times during document processing. When executed out-of-band, this command corrupts memory structures within the interpreter's heap, leading to unpredictable behavior including interpreter crashes, memory corruption, or potential code execution in the target system's memory space.
From an operational perspective, this vulnerability presents significant risk to organizations relying on Ghostscript for PDF processing, document conversion, or rendering services. Remote attackers can craft malicious PostScript files that trigger this memory corruption when processed by vulnerable systems, potentially leading to denial of service attacks or more severe exploitation scenarios. The vulnerability's impact extends beyond simple crashes as the memory corruption could enable attackers to manipulate the interpreter's internal state, potentially leading to privilege escalation or arbitrary code execution depending on the target system's security configuration and execution environment.
The flaw aligns with CWE-122 (Heap Overflow) and CWE-125 (Out-of-bounds Read) categories within the Common Weakness Enumeration framework, specifically demonstrating improper input validation and memory management issues in interpreted environments. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 (PostScript) and T1059.001 (Command and Scripting Interpreter) techniques, enabling adversaries to leverage PostScript processing capabilities for code execution. The vulnerability also relates to T1499.004 (Endpoint Denial of Service) and potentially T1068 (Exploitation for Privilege Escalation) depending on the system's execution context and privileges.
Organizations should immediately implement mitigation strategies including upgrading to Ghostscript version 9.24 or later where this vulnerability has been resolved through proper command validation and context restriction. Additionally, administrators should implement strict input validation for all PostScript processing, deploy network segmentation to limit exposure, and consider implementing sandboxing techniques to contain potential exploitation attempts. The recommended remediation approach includes comprehensive patch management, regular security assessments of document processing systems, and implementation of automated monitoring for suspicious PostScript file processing activities to detect potential exploitation attempts.