CVE-2019-6116 in Ghostscript
Summary
by MITRE
In Artifex Ghostscript through 9.26, ephemeral or transient procedures can allow access to system operators, leading to remote code execution.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability identified as CVE-2019-6116 represents a critical security flaw in Artifex Ghostscript versions prior to 9.27, where ephemeral or transient procedures can inadvertently grant access to system operators within the PostScript interpreter environment. This vulnerability stems from the improper handling of procedure objects that are created temporarily during execution but retain access to privileged system resources. The flaw exists in the interpreter's procedure management system where transient procedures can escape their intended scope and gain unauthorized access to system-level operations that should remain restricted to privileged contexts.
The technical exploitation of this vulnerability occurs through the manipulation of PostScript procedure objects that are designed to be temporary or ephemeral in nature. When these procedures are improperly managed during execution, they can retain references to system operators such as systemdict entries or privileged commands that should not be accessible to untrusted code. This creates a path where malicious PostScript code can leverage these transient procedures to execute arbitrary system commands, effectively bypassing the security boundaries that normally protect the interpreter from direct system access. The vulnerability specifically impacts the way Ghostscript handles procedure objects during the execution lifecycle, where temporary procedures are not properly isolated from system resources.
The operational impact of CVE-2019-6116 is severe and far-reaching, as it enables remote code execution capabilities that can be exploited by attackers to compromise systems running vulnerable Ghostscript versions. This vulnerability affects any application or service that relies on Ghostscript for processing PostScript or PDF documents, including web applications, document conversion services, and print servers. The remote execution capability means that an attacker can potentially execute arbitrary code on the target system without requiring local access, making this vulnerability particularly dangerous in networked environments. The vulnerability can be exploited through maliciously crafted PostScript or PDF files that trigger the problematic procedure handling behavior, leading to potential system compromise, data exfiltration, or further lateral movement within the network.
This vulnerability aligns with CWE-264, which addresses permissions, privileges, and access control issues, specifically focusing on the improper handling of system resources and access control boundaries within the interpreter. The flaw also maps to ATT&CK technique T1059.007 for command and scripting interpreter, as it enables the execution of arbitrary commands through the PostScript interpreter. Additionally, the vulnerability demonstrates characteristics of T1203, legitimate credentials, as it can be exploited to gain elevated privileges and execute system-level operations. Organizations using Ghostscript should prioritize immediate patching to version 9.27 or later, as this release includes fixes that properly isolate transient procedures from system resources and implement stricter access controls. Network segmentation and content filtering measures should be implemented as additional defensive controls to limit exposure to potentially malicious PostScript or PDF content.
The remediation approach requires immediate deployment of Ghostscript version 9.27 or later, which addresses the procedure isolation issue through enhanced memory management and access control mechanisms. Security administrators should also implement comprehensive monitoring for suspicious PostScript or PDF processing activities, particularly in environments where untrusted documents are processed. The fix involves strengthening the interpreter's procedure lifecycle management to ensure that ephemeral procedures cannot maintain references to system operators or privileged resources beyond their intended execution scope. Organizations should conduct thorough vulnerability assessments to identify all systems running vulnerable Ghostscript versions and implement automated patch management processes to maintain security posture against similar future vulnerabilities.