CVE-2017-6845 in PoDoFo
Summary
by MITRE
The PoDoFo::PdfColor::operator function in PdfColor.cpp in PoDoFo 0.9.4 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted file.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6845 represents a critical denial of service flaw within the PoDoFo PDF processing library version 0.9.4. This issue specifically affects the PoDoFo::PdfColor::operator function located in the PdfColor.cpp source file, demonstrating how seemingly minor code elements can create substantial security risks in document processing systems. The flaw manifests when the library encounters specially crafted PDF files that trigger a NULL pointer dereference during color handling operations, potentially disrupting legitimate document processing workflows and affecting applications that rely on PoDoFo for PDF manipulation.
The technical nature of this vulnerability stems from inadequate input validation within the PdfColor::operator function, which fails to properly handle malformed color specifications in PDF documents. When processing a crafted PDF file containing malicious color data, the function attempts to dereference a NULL pointer, leading to an application crash or system hang. This behavior aligns with CWE-476, which categorizes NULL pointer dereference as a common weakness in software security. The vulnerability operates at the boundary between user-supplied data and internal library processing, making it particularly dangerous in environments where untrusted PDF files are processed without proper sanitization.
From an operational perspective, this vulnerability creates significant risks for organizations relying on PoDoFo for document management, PDF generation, or processing tasks. Attackers can exploit this weakness by preparing malicious PDF files that, when opened or processed by applications using the vulnerable library, cause immediate service disruption. The impact extends beyond simple application crashes to potentially affect broader system availability, especially in server environments where PDF processing is a core function. This vulnerability particularly affects web applications, document management systems, and any software that accepts user-uploaded PDF files for processing, creating a substantial attack surface for denial of service attacks.
The exploitation of CVE-2017-6845 demonstrates characteristics consistent with ATT&CK technique T1499.004, which involves network denial of service attacks targeting applications. Organizations should implement multiple layers of defense including input validation, sandboxing of PDF processing operations, and regular security updates to mitigate this risk. The vulnerability also highlights the importance of proper error handling and memory management in library code, as the flaw could have been prevented through defensive programming practices such as null pointer checks before dereferencing operations. Remediation efforts should prioritize immediate patching of PoDoFo to version 0.9.5 or later, while implementing additional safeguards such as PDF file validation and restricted processing environments to prevent exploitation of similar vulnerabilities in other components of the document processing pipeline.