CVE-2018-9955 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 XFA resolveNode method of Button elements. 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-5531.
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Analysis
by VulDB Data Team • 02/06/2020
CVE-2018-9955 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.0.1.1049, classified under CWE-476 as "NULL Pointer Dereference" within the XFA (XML Forms Architecture) processing component. The vulnerability resides specifically in the resolveNode method of Button elements, where the software fails to validate object existence before performing operations on potentially null references. This fundamental flaw creates a dangerous condition where maliciously crafted PDF documents can trigger unauthorized code execution when processed by the vulnerable application. The vulnerability requires user interaction to exploit, meaning attackers must convince victims to visit malicious web pages or open compromised PDF files containing specially crafted XFA elements that trigger the vulnerable code path.
The technical exploitation of this vulnerability leverages the absence of proper input validation within the XFA parsing engine, specifically targeting the Button element's resolveNode method. When Foxit Reader encounters a malicious XFA structure, the application attempts to resolve node references without first verifying that the target objects exist, leading to a NULL pointer dereference that can be manipulated to execute arbitrary code with the privileges of the current user process. This type of vulnerability aligns with ATT&CK technique T1203 as it involves the exploitation of application vulnerabilities for code execution, and represents a classic heap-based buffer overflow scenario where memory corruption leads to arbitrary code execution. The vulnerability's impact extends beyond simple code execution to potentially allow full system compromise when combined with other attack vectors or when the application runs with elevated privileges.
From an operational perspective, this vulnerability poses significant risk to organizations relying on Foxit Reader for document processing, as it enables attackers to execute malicious payloads without requiring physical access to systems. The requirement for user interaction makes it particularly dangerous in targeted phishing campaigns or social engineering attacks where victims are诱导ed to open malicious documents. The vulnerability's presence in the XFA processing module indicates that it affects PDF documents containing complex forms and interactive elements, making it particularly concerning for enterprise environments where such documents are commonly shared. Organizations must consider the attack surface expansion when evaluating the risk of this vulnerability, as it can be exploited through multiple vectors including web browsers, email attachments, and file sharing platforms that may open PDF files automatically.
Mitigation strategies for CVE-2018-9955 should include immediate patching of Foxit Reader installations to version 9.0.1.1050 or later, which contains the necessary fixes for the XFA processing vulnerability. Network-based defenses should implement PDF content filtering and sandboxing techniques to prevent malicious documents from reaching end users, while endpoint protection solutions should be configured to monitor for suspicious PDF processing activities. Security teams should also consider implementing user education programs to raise awareness about the risks of opening untrusted PDF files and the importance of verifying document sources before processing. Additionally, organizations should conduct regular vulnerability assessments to identify other potential attack vectors within their PDF processing infrastructure and ensure that all related software components are kept current with security updates. The vulnerability demonstrates the critical importance of input validation and proper error handling in document processing applications, as highlighted by industry standards and best practices for secure coding practices.