CVE-2018-19478 in Ghostscript
Summary
by MITRE
In Artifex Ghostscript before 9.26, a carefully crafted PDF file can trigger an extremely long running computation when parsing the file.
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Analysis
by VulDB Data Team • 06/22/2023
CVE-2018-19478 represents a significant performance degradation vulnerability within Artifex Ghostscript versions prior to 9.26, classified under CWE-400 as an excessive computation vulnerability. This flaw manifests when processing specifically crafted pdf files that contain maliciously constructed computational structures designed to trigger prolonged execution times during the parsing phase. The vulnerability exploits inherent weaknesses in the pdf parser implementation where certain mathematical or recursive constructs can cause the system to engage in computationally intensive operations that may take extended periods to complete.
The technical nature of this vulnerability stems from insufficient input validation and lack of computational resource limits during pdf parsing operations. When Ghostscript encounters these specially crafted pdf files, the parser engine begins executing complex mathematical algorithms or recursive operations that spiral into extended computation cycles. This behavior can be leveraged by attackers to perform denial of service attacks against systems processing pdf documents, as the vulnerable software becomes unresponsive or extremely slow during the parsing phase.
The operational impact of CVE-2018-19478 extends beyond simple performance degradation to encompass potential system availability compromise. Organizations relying on Ghostscript for pdf processing, document conversion, or printing services face significant risk when handling untrusted pdf content. The vulnerability can be exploited in various attack scenarios including email attachments, web uploads, or document management systems where pdf files are automatically processed without proper sanitization. This makes it particularly dangerous in enterprise environments where pdf processing is automated and continuous.
Mitigation strategies for CVE-2018-19478 primarily involve upgrading to Ghostscript version 9.26 or later, which includes patches addressing the excessive computation vulnerability. System administrators should implement additional protective measures such as setting resource limits on pdf processing operations, implementing input validation for pdf files, and deploying sandboxing mechanisms to contain potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for resource exhaustion attacks and should be considered in broader security posture assessments. Organizations should also implement monitoring for unusual processing times and establish automated alerts for extended parsing operations that may indicate exploitation attempts.
The vulnerability demonstrates the critical importance of input validation and computational resource management in document processing software. It highlights how seemingly benign file formats can be weaponized to cause system instability and availability issues. Security teams should conduct regular vulnerability assessments of document processing systems and maintain updated threat intelligence regarding similar computational vulnerabilities in widely used software libraries. The incident underscores the necessity of implementing defense-in-depth strategies including network segmentation, access controls, and regular security updates to protect against such exploitation vectors.