CVE-2018-9967 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.1.1049. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of Format actions of TextBox objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code under the context of the current process. Was ZDI-CAN-5571.
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Analysis
by VulDB Data Team • 08/15/2024
The vulnerability identified as CVE-2018-9967 represents a critical remote code execution flaw affecting Foxit Reader version 9.0.1.1049, demonstrating a classic object validation weakness that has significant implications for document processing applications. This vulnerability resides within the PDF rendering engine's handling of TextBox objects, specifically in the Format action processing mechanism where proper object validation procedures are absent. The flaw stems from insufficient input sanitization and object existence verification before executing operations on potentially malformed PDF elements, creating an attack surface that can be exploited through maliciously crafted PDF documents or web pages. The vulnerability's classification aligns with CWE-476 which addresses null pointer dereference issues, though this particular case involves a more complex object validation failure rather than simple pointer dereferencing.
The operational impact of this vulnerability extends beyond typical document processing risks as it enables full remote code execution under the privileges of the Foxit Reader process. Attackers can craft malicious PDF files containing specially formatted TextBox objects with malformed Format actions that trigger the vulnerability when the document is opened or when specific interactive elements are accessed. The requirement for user interaction through visiting malicious web pages or opening malicious files aligns with attack patterns described in the MITRE ATT&CK framework under initial access and execution phases, specifically targeting the exploitation of application vulnerabilities. This vulnerability essentially allows adversaries to bypass traditional security controls by leveraging the legitimate PDF processing capabilities of the application to deliver malicious payloads.
The technical exploitation mechanism relies on the absence of proper object validation within the PDF parser's TextBox handling routines, where the application assumes object existence without verification before performing operations. This creates a condition where an attacker can manipulate the PDF structure to reference non-existent objects or objects in invalid states, causing the application to execute unintended code paths. The vulnerability's exploitation typically involves crafting PDF documents with carefully constructed TextBox elements that, when processed by Foxit Reader, trigger the validation gap and allow arbitrary code execution. This represents a serious security flaw in the application's defensive programming practices and highlights the importance of input validation and object state verification in security-critical applications. The vulnerability's existence demonstrates the critical need for robust defensive measures in document processing applications that handle untrusted input, as these applications often run with elevated privileges to provide full document functionality. Organizations utilizing Foxit Reader should implement immediate mitigations including software updates, network-based restrictions, and user education to prevent exploitation of this vulnerability. The flaw's resolution requires proper input validation and object existence checks before any operations are performed on PDF elements, aligning with security best practices outlined in industry standards and threat modeling frameworks.