CVE-2008-6679 in Ghostscript
Summary
by MITRE
Buffer overflow in the BaseFont writer module in Ghostscript 8.62, and possibly other versions, allows remote attackers to cause a denial of service (ps2pdf crash) and possibly execute arbitrary code via a crafted Postscript file.
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Analysis
by VulDB Data Team • 09/01/2019
The vulnerability identified as CVE-2008-6679 represents a critical buffer overflow flaw within the BaseFont writer module of Ghostscript version 8.62 and potentially other iterations in the software lineage. This issue resides in the handling of PostScript file processing where the software fails to properly validate input data lengths before writing to memory buffers. The flaw manifests when a maliciously crafted PostScript document is processed by Ghostscript's ps2pdf utility, which serves as a converter from PostScript to Portable Document Format. The buffer overflow occurs during the parsing and rendering of font data within the BaseFont module, where insufficient bounds checking allows an attacker to overwrite adjacent memory locations.
The technical exploitation of this vulnerability leverages the inherent weakness in memory management practices within the Ghostscript codebase, specifically within the font handling subsystem. When processing a specially crafted PostScript file containing malformed font data, the BaseFont writer module attempts to write data beyond the allocated buffer boundaries. This condition creates a situation where the program's execution flow can be disrupted or potentially controlled by an attacker who has crafted the input to manipulate memory contents. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and potentially CWE-122 for heap-based buffer overflows depending on the specific memory allocation patterns used during font processing.
From an operational standpoint, this vulnerability presents significant risks to organizations relying on Ghostscript for document processing and conversion services. The remote exploitation capability means that attackers can potentially compromise systems without requiring local access, making it particularly dangerous in networked environments where document conversion services are exposed. The primary impact manifests as denial of service through application crashes, but the potential for arbitrary code execution introduces additional security concerns. Attackers could leverage this vulnerability to execute malicious payloads on systems running vulnerable versions of Ghostscript, potentially leading to complete system compromise. The ps2pdf utility, being a common component in many document processing pipelines, increases the attack surface significantly.
The attack vector for this vulnerability typically involves sending a malicious PostScript file to a system running vulnerable Ghostscript software, particularly when the system processes documents through the ps2pdf conversion utility. This could occur in web applications that accept document uploads, email servers processing PostScript attachments, or print servers handling document conversion. The vulnerability's impact extends beyond simple service disruption as it represents a potential path for privilege escalation and persistent access within compromised environments. Organizations using Ghostscript in production environments should consider implementing input validation measures and restricting access to conversion utilities to minimize exposure. The ATT&CK framework categorizes this vulnerability under T1203, which covers exploitation of remote services, and potentially T1059 for command and script injection techniques that could be employed once initial access is gained.
Mitigation strategies for CVE-2008-6679 should prioritize immediate software updates to patched versions of Ghostscript where available. System administrators should also implement input sanitization measures, particularly for PostScript files processed through Ghostscript utilities, and consider network segmentation to limit exposure of vulnerable services. Additional protective measures include monitoring for suspicious document processing activities, implementing sandboxing techniques for document conversion, and maintaining up-to-date security patches across all systems utilizing Ghostscript components. Organizations should also conduct vulnerability assessments to identify all instances of vulnerable Ghostscript installations and ensure proper access controls are in place to prevent unauthorized use of document conversion utilities. The implementation of intrusion detection systems capable of identifying malicious PostScript file patterns can provide additional layers of defense against exploitation attempts targeting this vulnerability.