CVE-2017-14977 in Poppler
Summary
by MITRE
The FoFiTrueType::getCFFBlock function in FoFiTrueType.cc in Poppler 0.59.0 has a NULL pointer dereference vulnerability due to lack of validation of a table pointer, which allows an attacker to launch a denial of service attack.
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Analysis
by VulDB Data Team • 12/30/2022
The vulnerability identified as CVE-2017-14977 represents a critical NULL pointer dereference flaw within the Poppler PDF rendering library version 0.59.0. This issue specifically affects the FoFiTrueType::getCFFBlock function located in the FoFiTrueType.cc source file, demonstrating a fundamental lack of input validation that creates an exploitable condition for malicious actors. The vulnerability stems from insufficient validation of table pointers during the processing of TrueType font structures, which are commonly embedded within PDF documents to ensure proper text rendering across different systems.
The technical implementation of this flaw occurs when Poppler attempts to process font data within PDF files, particularly those containing TrueType fonts with Compact Font Format (CFF) data structures. When the FoFiTrueType::getCFFBlock function processes font information, it fails to properly validate whether the table pointer is NULL before attempting to access or dereference it. This validation gap creates a scenario where an attacker can craft a malicious PDF file containing specially constructed font data that triggers the NULL pointer dereference, causing the application to crash or become unresponsive. The vulnerability operates at the level of font processing within the PDF rendering pipeline, making it particularly dangerous as it can be triggered simply by opening a malicious document.
From an operational impact perspective, this vulnerability enables a remote denial of service attack that can be executed without requiring any special privileges or user interaction beyond opening the malicious PDF file. The attack vector is particularly concerning because PDF documents are widely used across all operating systems and applications, making this vulnerability potentially exploitable in numerous contexts including web browsers, email clients, and document viewers. The flaw affects any system running Poppler version 0.59.0 or earlier, which was widely deployed in various software applications, potentially creating a broad attack surface for adversaries seeking to disrupt services or systems through targeted PDF-based attacks.
The vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations, and represents a classic example of inadequate input validation that can be exploited to cause system instability. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and denial of service through application-level exploits, potentially enabling attackers to disrupt services or create conditions for more sophisticated attacks. The lack of proper error handling and input validation in the font processing pipeline demonstrates a common weakness in multimedia and document processing libraries where complex data structures must be parsed without adequate safeguards against malformed inputs.
Organizations and developers should immediately update to Poppler versions that contain the patched implementation of the FoFiTrueType::getCFFBlock function, which includes proper validation of table pointers before dereferencing. Additionally, implementing input sanitization measures and restricting PDF file processing to trusted sources can provide additional layers of protection. System administrators should consider deploying intrusion detection systems that can identify suspicious PDF file patterns and monitor for potential exploitation attempts. The vulnerability serves as a reminder of the importance of robust input validation in multimedia processing libraries and highlights the need for comprehensive security testing of font and graphics processing components within document rendering systems.