CVE-2017-14831 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 author attribute of Circle 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-5023.
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Analysis
by VulDB Data Team • 12/16/2019
The vulnerability identified as CVE-2017-14831 represents a critical remote code execution flaw affecting Foxit Reader version 8.3.1.21155, demonstrating a classic object validation weakness that has significant implications for document processing security. This vulnerability operates through the manipulation of Circle Annotation objects within PDF documents, specifically targeting the author attribute handling mechanism that fails to properly validate object existence before executing operations on it. The flaw resides in the application's failure to implement proper input sanitization and object validation checks, creating an exploitable condition where maliciously crafted PDF content can trigger unintended code execution. The vulnerability requires user interaction to be exploited, meaning that targets must either visit a malicious web page hosting the vulnerable PDF or open a crafted malicious file, which aligns with common attack vectors used in phishing and social engineering campaigns. This attack model follows the typical pattern described in the ATT&CK framework under initial access and execution phases, where adversaries leverage user trust to deliver malicious payloads through seemingly legitimate document formats.
The technical nature of this vulnerability stems from a fundamental flaw in the application's object handling architecture, specifically categorized under CWE-476 which addresses NULL pointer dereferences and improper object validation. When Foxit Reader processes a Circle Annotation object, it attempts to access the author attribute without first verifying whether the object reference is valid or has been properly initialized. This lack of proper validation creates a condition where an attacker can craft a malicious PDF containing specially constructed Circle Annotation objects that, when processed by the vulnerable reader, result in arbitrary code execution. The exploitation occurs at the application level where the reader's parsing engine encounters the malformed object and attempts operations on what appears to be a valid object reference but is actually pointing to invalid memory locations or manipulated data structures. The vulnerability is particularly dangerous because it allows execution under the context of the current process, meaning that successful exploitation can result in full system compromise depending on the privileges of the user running the vulnerable software.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a significant threat to enterprise security environments where document processing is common and user interaction is unavoidable. Organizations utilizing Foxit Reader for document review and collaboration are particularly at risk since the vulnerability can be triggered through web browsing activities or email attachments, making it a prime target for targeted attacks. The fact that this vulnerability was tracked as ZDI-CAN-5023 indicates it was recognized by the security community as a legitimate threat requiring immediate attention and remediation. The exploitation chain typically involves crafting a PDF file containing malicious Circle Annotation objects that, when opened or viewed by the vulnerable reader, trigger the code execution vulnerability. This vulnerability demonstrates the broader security challenge in document processing applications where complex file format parsers must handle a wide variety of input data while maintaining robust validation and sanitization mechanisms. The risk is compounded by the fact that PDF documents are commonly shared across organizations and can be easily distributed through multiple channels including email, web downloads, and file sharing systems.
Effective mitigation strategies for this vulnerability require immediate patching of the affected Foxit Reader versions, as the vendor would have released security updates addressing the specific object validation flaw in the Circle Annotation processing code. Organizations should implement comprehensive software update policies that ensure all document processing applications remain current with the latest security patches and updates. Network-level defenses such as web application firewalls and content filtering systems can provide additional protection by scanning PDF content for known malicious patterns or suspicious object structures. Security monitoring should include detection of unusual PDF processing activities or attempts to access invalid object references within document readers. The vulnerability highlights the importance of input validation and defensive programming practices in security-critical applications, emphasizing the need for proper object existence checking before operations are performed. Organizations should also consider implementing user education programs to raise awareness about the risks of opening untrusted PDF files and the importance of maintaining updated security software. This vulnerability serves as a reminder of the critical importance of secure coding practices and the need for regular security assessments of document processing applications that handle untrusted input data.