CVE-2017-7948 in Ghostscript
Summary
by MITRE
Integer overflow in the mark_curve function in Artifex Ghostscript 9.21 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via a crafted PostScript document.
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Analysis
by VulDB Data Team • 12/01/2022
The vulnerability identified as CVE-2017-7948 represents a critical integer overflow condition within the mark_curve function of Artifex Ghostscript version 9.21. This flaw exists in the handling of PostScript document processing where the software fails to properly validate integer values during curve marking operations. The issue manifests when processing maliciously crafted PostScript files that contain malformed curve data, leading to arithmetic overflow conditions that can result in memory corruption. The vulnerability resides in the core rendering engine of Ghostscript, which is widely used for processing PostScript and PDF documents across various platforms and applications. This integer overflow occurs during the mathematical calculations involved in rendering curved graphics elements, where the software attempts to compute memory offsets or buffer sizes using values that exceed the maximum representable integer limits, causing unexpected behavior in the memory management subsystem.
The technical exploitation of this vulnerability enables remote attackers to trigger out-of-bounds write operations that can corrupt adjacent memory regions, leading to application crashes and potential denial of service conditions. The integer overflow specifically affects the mark_curve function which is responsible for identifying and marking curve segments within PostScript graphics. When the function processes malformed input data, the overflow causes the software to allocate insufficient memory buffers or calculate incorrect memory addresses, resulting in memory corruption that can be leveraged to crash the application. This vulnerability is particularly dangerous because it can be triggered remotely through the processing of untrusted PostScript documents, making it suitable for exploitation in web-based attack scenarios where users might inadvertently open malicious documents. The flaw can also potentially allow for more sophisticated attacks depending on the memory layout and the specific nature of the overflow, though the primary impact remains denial of service and application instability.
The operational impact of CVE-2017-7948 extends beyond simple service disruption to potentially compromise system availability in environments where Ghostscript is integrated into critical document processing workflows. Organizations relying on Ghostscript for PDF generation, conversion, or document rendering may experience significant downtime when vulnerable systems process malicious documents, particularly in automated processing environments where unattended document handling occurs. The vulnerability affects a broad range of systems including servers, workstations, and cloud environments where Ghostscript is deployed, making it a widespread concern for security administrators. Attackers could leverage this vulnerability to perform persistent denial of service attacks against systems processing PostScript content, potentially disrupting business operations and user access to document services. The vulnerability's remote exploitation capability means that attackers do not require local access to target systems, making it particularly dangerous in networked environments where document processing occurs automatically.
Mitigation strategies for CVE-2017-7948 should focus on immediate patching of affected Ghostscript installations to version 9.22 or later, which contains the necessary fixes for the integer overflow condition. System administrators should implement strict document validation procedures for all PostScript content processed through Ghostscript, including sandboxing or containerization of document processing environments to limit potential damage from exploitation attempts. Network security controls such as content filtering and email scanning should be enhanced to detect and block potentially malicious PostScript documents before they reach systems running vulnerable Ghostscript versions. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual application behavior or crash patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses issues where integer arithmetic operations produce results that exceed the maximum value representable by the data type, and can be mapped to ATT&CK technique T1203, Exploitation for Client Execution, when considering the remote execution capabilities through document processing. Additionally, this vulnerability demonstrates characteristics of ATT&CK technique T1059, Command and Scripting Interpreter, as it involves the execution of malicious code through interpreter-based document formats. Regular security assessments and vulnerability scanning should be conducted to ensure that all systems utilizing Ghostscript remain patched and protected against similar integer overflow vulnerabilities in the future.