CVE-2009-4117 in PDF
Summary
by MITRE
Multiple stack-based buffer overflows in pdf_shade4.c in MuPDF before commit 20091125231942, as used in SumatraPDF before 1.0.1, allow remote attackers to cause a denial of service and possibly execute arbitrary code via a /Decode array for certain types of shading that are not properly handled by the (1) pdf_loadtype4shade, (2) pdf_loadtype5shade, (3) pdf_loadtype6shade, and (4) pdf_loadtype7shade functions. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 09/16/2024
The vulnerability described in CVE-2009-4117 represents a critical stack-based buffer overflow condition affecting the MuPDF library implementation within SumatraPDF document viewer. This flaw exists in the pdf_shade4.c file and specifically targets four distinct shading functions: pdf_loadtype4shade, pdf_loadtype5shade, pdf_loadtype6shade, and pdf_loadtype7shade. The vulnerability manifests when processing PDF documents containing malformed /Decode arrays in certain types of shading operations, creating an exploitable condition that can be leveraged by remote attackers to compromise system integrity.
The technical exploitation of this vulnerability stems from improper bounds checking within the shading parsing functions. When MuPDF encounters a malformed /Decode array in shading operations, the software fails to validate input parameters before attempting to copy data into fixed-size stack buffers. This inadequate validation allows attackers to overflow these buffers and potentially overwrite adjacent memory locations including return addresses and function pointers. The vulnerability is particularly dangerous because it can be triggered through remote PDF document loading, making it an attractive target for drive-by attacks. According to CWE-121, this represents a classic stack-based buffer overflow condition where insufficient bounds checking enables attackers to overwrite stack data.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling arbitrary code execution on vulnerable systems. When successful, attackers can manipulate the program execution flow by overwriting return addresses or other critical stack variables, allowing for code injection attacks. This makes the vulnerability particularly concerning for document viewer applications that automatically process PDF files from untrusted sources. The vulnerability affects SumatraPDF versions prior to 1.0.1 and the corresponding MuPDF library versions, highlighting the importance of keeping document processing software up to date. The attack vector requires remote delivery of a malicious PDF document, making it accessible to attackers who can host compromised content on web servers or distribute through email attachments.
Mitigation strategies for this vulnerability should focus on immediate software updates and input validation improvements. Organizations should prioritize updating to SumatraPDF version 1.0.1 or later, which contains patches addressing the buffer overflow conditions in the shading parsing functions. Additionally, implementing proper bounds checking in the pdf_shade4.c file would prevent the overflow conditions from occurring, aligning with ATT&CK technique T1203 for input validation and sanitization. Network-level protections such as PDF content filtering and sandboxing mechanisms can provide additional defense in depth. Security teams should also consider implementing automated vulnerability scanning to identify systems running vulnerable versions of MuPDF or SumatraPDF, as these applications are commonly used for document processing in enterprise environments. The vulnerability demonstrates the critical importance of proper memory management in PDF rendering libraries and the potential for remote code execution through seemingly benign document processing operations.