CVE-2019-9903 in Poppler
Summary
by MITRE
PDFDoc::markObject in PDFDoc.cc in Poppler 0.74.0 mishandles dict marking, leading to stack consumption in the function Dict::find() located at Dict.cc, which can (for example) be triggered by passing a crafted pdf file to the pdfunite binary.
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Analysis
by VulDB Data Team • 08/04/2023
The vulnerability identified as CVE-2019-9903 represents a critical stack-based buffer overflow condition within the Poppler PDF library version 0.74.0. This flaw exists in the PDFDoc::markObject function located in PDFDoc.cc, which improperly handles dictionary marking operations. The issue manifests when the Dict::find() function in Dict.cc processes maliciously crafted dictionary structures, creating a scenario where stack memory consumption becomes excessive and ultimately leads to a potential denial of service condition or arbitrary code execution. The vulnerability specifically affects the pdfunite binary, which is part of the Poppler suite used for combining PDF documents and processing PDF files in various applications.
The technical root cause of this vulnerability stems from inadequate input validation and improper memory management within the PDF parsing logic. When a crafted PDF file contains malformed dictionary structures, the PDFDoc::markObject function fails to properly handle the recursive dictionary traversal, causing the Dict::find() function to consume excessive stack space during its operation. This behavior aligns with CWE-129, which describes improper validation of array indices, and CWE-787, which covers out-of-bounds write conditions. The flaw demonstrates characteristics consistent with stack-based buffer overflow vulnerabilities where the attacker can manipulate the parsing process to cause uncontrolled stack consumption, potentially leading to application crashes or more severe consequences depending on the execution environment.
The operational impact of CVE-2019-9903 extends beyond simple denial of service scenarios, as it can be exploited in various attack vectors that leverage PDF processing capabilities. Applications that utilize Poppler for PDF manipulation, including web browsers, PDF viewers, document management systems, and security scanning tools, become vulnerable when processing untrusted PDF content. The vulnerability can be triggered through automated means when the pdfunite utility processes maliciously crafted PDF files, making it particularly dangerous in environments where PDF files are automatically processed or where users might inadvertently open crafted documents. Attackers could potentially exploit this vulnerability to cause application crashes, leading to service disruption, or in more sophisticated scenarios, leverage the stack corruption for privilege escalation or code execution, especially when the affected applications run with elevated privileges.
Mitigation strategies for CVE-2019-9903 should focus on immediate patching of the Poppler library to version 0.75.0 or later, where the vulnerability has been addressed through proper dictionary handling and stack consumption limits. Organizations should implement strict input validation for all PDF processing workflows, particularly when dealing with untrusted content, and consider deploying sandboxing mechanisms around PDF handling components. Additionally, network segmentation and access controls should be enforced to limit exposure to potentially malicious PDF files, while monitoring systems should be configured to detect unusual PDF processing patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of following ATT&CK framework principles for defensive measures, particularly in the context of privilege escalation and execution techniques that could be leveraged by adversaries to exploit similar memory corruption vulnerabilities in PDF processing libraries.