CVE-2017-7382 in PoDoFo
Summary
by MITRE
The PdfFontFactory.cpp:200:88 code in PoDoFo 0.9.5 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted PDF document.
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Analysis
by VulDB Data Team • 08/25/2020
The vulnerability identified as CVE-2017-7382 resides within the PoDoFo library version 0.9.5, specifically in the PdfFontFactory.cpp file at line 200, column 88. This flaw represents a classic null pointer dereference condition that can be exploited by remote attackers through the careful crafting of malicious PDF documents. The PoDoFo library serves as a widely-used open-source library for creating and modifying PDF files, making this vulnerability particularly concerning for applications that process untrusted PDF content. The vulnerability manifests when the library attempts to handle font data within PDF documents, where insufficient input validation leads to the dereferencing of a null pointer during font processing operations.
The technical execution of this vulnerability involves attackers constructing specially formatted PDF files that trigger the null pointer dereference condition when PoDoFo attempts to parse and render font information. When the library encounters malformed font data, it fails to properly validate the font structure before attempting to access memory locations, resulting in an application crash. This denial of service condition can be reliably triggered by any application that utilizes PoDoFo for PDF processing, effectively allowing attackers to disrupt service availability without requiring any special privileges or authentication. The vulnerability operates at the parsing layer of the PDF processing pipeline, making it particularly effective as a denial of service vector since it can be exploited through normal PDF document handling operations.
The operational impact of CVE-2017-7382 extends beyond simple application crashes to encompass broader service disruption scenarios across numerous software systems. Applications that depend on PoDoFo for PDF generation, modification, or rendering become vulnerable to this attack, including web applications, document management systems, and content processing platforms. The vulnerability aligns with CWE-476, which specifically addresses null pointer dereference conditions, and can be mapped to ATT&CK technique T1499.004 for network denial of service attacks. Organizations utilizing PoDoFo in production environments face significant risk of service interruption, as this vulnerability can be exploited by anyone with access to submit PDF documents to affected systems. The crash condition is particularly problematic because it can be triggered silently during normal document processing, potentially allowing attackers to maintain persistent disruption without detection.
Mitigation strategies for CVE-2017-7382 focus primarily on upgrading to patched versions of the PoDoFo library where the null pointer dereference has been addressed through proper input validation and error handling. System administrators should immediately update all affected applications to PoDoFo versions that contain the fix, typically released in subsequent patches following the vulnerability disclosure. Additionally, implementing input validation measures at the application level can provide defense in depth, including sanitizing PDF inputs before processing and implementing timeouts for PDF handling operations. Network-level protections such as PDF content filtering and sandboxing mechanisms can also reduce the attack surface by preventing malformed documents from reaching vulnerable applications. Organizations should also consider implementing monitoring and alerting for application crashes or unusual processing patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of robust input validation in document processing libraries and highlights the need for comprehensive security testing of third-party components used in critical applications.