CVE-2017-14833 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 8.3.1.21155. 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 style attribute of Text Annotation 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-5025.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-14833 represents a critical code execution vulnerability affecting Foxit Reader version 8.3.1.21155 that demonstrates a classic null pointer dereference flaw in the PDF processing engine. This vulnerability resides within the handling of Text Annotation objects, specifically in how the software processes the style attribute of these annotations. The flaw occurs when the application attempts to perform operations on an object without first validating whether that object actually exists within the document structure. This type of vulnerability falls under CWE-476 which categorizes null pointer dereference issues, and it aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute malicious code. The vulnerability requires user interaction to be exploited, meaning an attacker must convince a victim to visit a malicious webpage or open a specially crafted PDF file containing the malicious annotation. When the vulnerable Foxit Reader processes such a document, it attempts to access an object that has not been properly initialized or validated, leading to a crash that can be leveraged for arbitrary code execution.
The technical exploitation of this vulnerability demonstrates how improper input validation in PDF rendering engines can create dangerous attack vectors. When Foxit Reader encounters a Text Annotation with a malformed style attribute, the application's internal processing logic fails to check if the referenced object exists before attempting to access its properties. This creates a scenario where the program attempts to execute operations on a null reference, potentially leading to memory corruption that attackers can manipulate to inject and execute malicious code. The vulnerability is particularly concerning because it operates at the application level within the PDF rendering context, meaning that successful exploitation can occur without requiring elevated privileges beyond those of the currently logged-in user. The attack surface is broadened by the fact that PDF documents are commonly shared through email attachments, web downloads, and document sharing platforms, making this vulnerability highly exploitable in real-world scenarios. The vulnerability's classification as a remote code execution issue means that attackers do not need physical access to the target system, and can potentially compromise systems through simple web browsing or document opening activities.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential full system compromise, especially when considering that Foxit Reader typically runs with the privileges of the current user. Attackers can leverage this vulnerability to establish persistent access, escalate privileges, or deploy additional malware components within the victim's environment. The fact that this vulnerability affects a widely used PDF reader means that the potential attack surface is extensive, as millions of users worldwide rely on Foxit Reader for document viewing. Organizations that have not patched this vulnerability remain at risk of targeted attacks, particularly in environments where users frequently open documents from untrusted sources. The vulnerability also highlights the importance of proper object validation in software applications, as the lack of pre-validation checks creates predictable exploitation patterns. Security professionals should note that this vulnerability represents a common pattern in PDF processing engines where insufficient input sanitization leads to code execution flaws, making it a valuable case study for understanding how seemingly minor validation gaps can create major security risks in document processing applications.
Mitigation strategies for CVE-2017-14833 should focus on immediate patch deployment, as the vulnerability has been addressed through official security updates from Foxit Corporation. Organizations should implement comprehensive patch management procedures to ensure all instances of Foxit Reader are updated promptly. Additional protective measures include deploying web application firewalls, implementing content filtering solutions, and educating users about the risks of opening suspicious PDF files or visiting untrusted websites. Network segmentation and privilege separation can help limit the potential impact if exploitation occurs. Security monitoring should include detection of anomalous PDF processing activities and unusual network connections that might indicate exploitation attempts. Organizations should also consider implementing sandboxing techniques for PDF document handling and regularly audit their PDF processing environments for similar validation flaws. The vulnerability underscores the critical importance of regular security assessments and code reviews focusing on input validation and object handling within document processing applications, particularly those handling complex file formats like PDF.