CVE-2018-11645 in Ghostscript
Summary
by MITRE
psi/zfile.c in Artifex Ghostscript before 9.21rc1 permits the status command even if -dSAFER is used, which might allow remote attackers to determine the existence and size of arbitrary files, a similar issue to CVE-2016-7977.
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Analysis
by VulDB Data Team • 03/19/2023
The vulnerability identified as CVE-2018-11645 resides within the Ghostscript document processing software developed by Artifex, specifically in the psi/zfile.c component. This flaw represents a critical security oversight that undermines the intended sandboxing mechanisms of the software when the -dSAFER parameter is employed. The issue allows malicious actors to bypass intended security restrictions and gain unauthorized knowledge about file system structures, potentially exposing sensitive information about the underlying operating system's file hierarchy.
The technical implementation of this vulnerability stems from the improper handling of the status command within the Ghostscript interpreter when executing under safe mode. The -dSAFER flag is designed to restrict access to system resources and prevent potentially dangerous operations, but the flaw in psi/zfile.c permits execution of the status command regardless of this safety restriction. This command typically retrieves file metadata including existence status and file size information, which when exposed can provide attackers with detailed reconnaissance data about the target system's file structure and potentially sensitive files.
From an operational impact perspective, this vulnerability creates a significant information disclosure risk that can be exploited by remote attackers to perform reconnaissance activities. The ability to determine file existence and size remotely allows attackers to map file systems and identify potentially sensitive or valuable files without direct access to their contents. This capability aligns with ATT&CK technique T1083 (File and Directory Discovery) and represents a precursor to more sophisticated attacks that could leverage this information for privilege escalation or data exfiltration. The vulnerability is particularly concerning because it operates at the interpreter level, meaning it can be exploited through various input formats that Ghostscript processes, including PostScript and PDF documents.
The security implications extend beyond simple information disclosure, as this vulnerability can be chained with other exploits to create more comprehensive attack vectors. Attackers could use the information gathered through this vulnerability to target specific files for further exploitation or to craft more sophisticated attacks that leverage knowledge of the target system's file structure. The flaw demonstrates a failure in proper access control implementation and highlights the importance of maintaining strict separation between safe and unsafe operations within interpreted environments. This vulnerability directly relates to CWE-250 (Execute Code from Untrusted Input) and CWE-352 (Cross-Site Request Forgery) in its ability to bypass intended security controls and provide unauthorized access to system information. Organizations utilizing Ghostscript for document processing and rendering should immediately implement mitigations including updating to versions 9.21rc1 or later, implementing network segmentation to limit exposure, and monitoring for suspicious file access patterns that might indicate exploitation attempts.