CVE-2009-0196 in Ghostscript
Summary
by MITRE
Heap-based buffer overflow in the big2_decode_symbol_dict function (jbig2_symbol_dict.c) in the JBIG2 decoding library (jbig2dec) in Ghostscript 8.64, and probably earlier versions, allows remote attackers to execute arbitrary code via a PDF file with a JBIG2 symbol dictionary segment with a large run length value.
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Analysis
by VulDB Data Team • 09/01/2019
The vulnerability identified as CVE-2009-0196 represents a critical heap-based buffer overflow within the JBIG2 decoding functionality of Ghostscript version 8.64 and potentially earlier releases. This flaw exists in the big2_decode_symbol_dict function located in the jbig2_symbol_dict.c source file, which forms part of the jbig2dec library implementation. The vulnerability manifests when processing PDF files containing JBIG2 symbol dictionary segments with excessively large run length values, creating a condition where attacker-controlled input can overwrite adjacent heap memory regions.
The technical exploitation of this vulnerability stems from inadequate input validation within the JBIG2 decoding process. When the big2_decode_symbol_dict function processes symbol dictionary segments, it fails to properly bounds-check the run length values provided in the JBIG2 data structure. This allows an attacker to craft malicious PDF documents containing specially constructed JBIG2 segments where the run length parameter exceeds the allocated buffer size. The heap-based overflow occurs because the function allocates memory based on the attacker-provided run length value without sufficient validation, leading to memory corruption that can be leveraged for arbitrary code execution.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a remote code execution vector that can be exploited through web browsers or PDF processing applications that utilize Ghostscript's JBIG2 decoding capabilities. Attackers can deliver malicious PDF files through various channels including email attachments, compromised websites, or document sharing platforms, making this vulnerability particularly dangerous in enterprise environments where PDF processing is common. The vulnerability affects not only the direct Ghostscript installation but also any applications that depend on Ghostscript's JBIG2 decoding functionality, including various PDF viewers, document conversion tools, and web applications that process PDF documents.
Security professionals should note that this vulnerability aligns with CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory regions. The attack pattern follows typical remote exploitation techniques described in MITRE ATT&CK framework under the T1059.007 technique for command and script injection. Organizations should prioritize immediate patching of affected Ghostscript installations, as the vulnerability provides direct execution capabilities without requiring additional exploitation primitives. The fix typically involves implementing proper bounds checking on run length values and ensuring that memory allocation respects reasonable limits to prevent heap corruption.
Mitigation strategies should include immediate deployment of patched Ghostscript versions, implementation of PDF file scanning and filtering mechanisms, and network-based restrictions on JBIG2 content processing. System administrators should also consider disabling JBIG2 decoding functionality entirely if it is not required for business operations. Additionally, organizations should implement monitoring for suspicious PDF processing activities and maintain updated threat intelligence feeds to detect potential exploitation attempts targeting this vulnerability. The vulnerability demonstrates the importance of input validation in multimedia processing libraries and highlights the need for comprehensive security testing of document parsing components that handle complex binary formats.