CVE-2009-4897 in Gpl Ghostscript
Summary
by MITRE
Buffer overflow in gs/psi/iscan.c in Ghostscript 8.64 and earlier allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted PDF document containing a long name.
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Analysis
by VulDB Data Team • 09/20/2021
The vulnerability identified as CVE-2009-4897 represents a critical buffer overflow flaw within the Ghostscript document processing library version 8.64 and earlier. This issue resides in the gs/psi/iscan.c file which handles the parsing of PDF documents, specifically when processing names that exceed expected length parameters. The flaw manifests when Ghostscript encounters a crafted PDF document containing an excessively long name field, creating a condition where memory boundaries are exceeded during the parsing operation.
This buffer overflow vulnerability operates through the manipulation of PDF name objects, which are fundamental components used to identify various elements within PDF documents including fonts, images, and other resources. When Ghostscript processes these malformed name fields, the insufficient bounds checking in the iscan.c module allows attackers to overwrite adjacent memory locations with controlled data. The vulnerability is particularly dangerous because it can be triggered remotely through the processing of malicious PDF documents without requiring user interaction or special privileges.
The operational impact of this vulnerability extends beyond simple denial of service to encompass full arbitrary code execution capabilities. Attackers can leverage this flaw to inject and execute malicious code within the context of the Ghostscript process, potentially leading to complete system compromise. The memory corruption resulting from the buffer overflow can be exploited to redirect program execution flow, overwrite critical function pointers, or manipulate stack-based variables to achieve unauthorized code execution. This makes the vulnerability particularly attractive to threat actors seeking persistent access to systems that process PDF documents.
From a cybersecurity perspective, this vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1059.007 for execution through command and scripting interpreter. The vulnerability demonstrates poor input validation and memory management practices that are common in legacy software systems. Organizations processing PDF documents through Ghostscript are at significant risk, particularly those in environments where untrusted documents are handled such as email servers, web applications, and document management systems. The remote exploitability of this vulnerability means that simply opening or processing a malicious PDF document can lead to system compromise without any user interaction.
Mitigation strategies for CVE-2009-4897 require immediate patching of Ghostscript installations to versions 8.65 or later where the buffer overflow has been addressed through proper bounds checking and memory allocation practices. Organizations should also implement defensive measures including PDF document sanitization, content filtering, and network-based intrusion detection systems to identify and block malicious PDF content. Additionally, system administrators should consider implementing sandboxing techniques for PDF processing and regularly monitoring for exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date software libraries and implementing comprehensive security testing procedures for document processing applications to prevent similar issues from occurring in other components of the software stack.