CVE-2017-14975 in Poppler
Summary
by MITRE
The FoFiType1C::convertToType0 function in FoFiType1C.cc in Poppler 0.59.0 has a NULL pointer dereference vulnerability because a data structure is not initialized, which allows an attacker to launch a denial of service attack.
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Analysis
by VulDB Data Team • 05/26/2020
The vulnerability identified as CVE-2017-14975 resides within the Poppler PDF rendering library version 0.59.0, specifically in the FoFiType1C::convertToType0 function located in the FoFiType1C.cc source file. This flaw represents a critical NULL pointer dereference vulnerability that fundamentally stems from improper initialization of a data structure within the font processing code. The vulnerability manifests when the library attempts to process Type1C font data structures, which are commonly found in PDF documents and used for font rendering. The absence of proper initialization creates a scenario where a pointer variable remains uninitialized, leading to unpredictable behavior when the code attempts to dereference this NULL pointer during font conversion operations.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious PDF document containing specially formatted Type1C font data that triggers the flawed conversion function. When the Poppler library processes such a document, it invokes the FoFiType1C::convertToType0 function without proper validation of the data structure initialization state. This results in the execution attempting to access memory through a NULL pointer reference, causing the application to crash and terminate abruptly. The vulnerability directly maps to CWE-476 which defines NULL Pointer Dereference as a condition where a null value is used as a pointer reference, leading to application instability and potential denial of service conditions.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted PDF content, including web applications, email servers, and document management systems. The denial of service attack vector allows remote attackers to disrupt services by simply sending malicious PDF files that trigger the NULL pointer dereference. This affects a wide range of applications that rely on Poppler for PDF rendering, including web browsers, document viewers, and server-side PDF processing systems. The impact extends beyond simple service disruption as it can be leveraged in larger attack chains where attackers might use this vulnerability to destabilize systems before attempting more sophisticated exploits.
The mitigation strategies for this vulnerability primarily involve upgrading to Poppler version 0.60.0 or later, where the NULL pointer dereference has been addressed through proper initialization of the affected data structures. System administrators should also implement defensive measures such as validating PDF content before processing, employing sandboxing techniques, and monitoring for unusual application termination patterns. Additionally, organizations should consider implementing content filtering mechanisms that can detect and block potentially malicious PDF files based on known attack patterns. The vulnerability demonstrates the importance of proper input validation and initialization practices in security-critical code, aligning with ATT&CK technique T1499.004 which covers network disruption through denial of service attacks. Organizations should also maintain comprehensive patch management processes to ensure timely deployment of security updates and consider implementing automated vulnerability scanning tools to identify systems running vulnerable versions of the Poppler library.