CVE-2019-6771 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to disclose sensitive information on vulnerable installations of Foxit Reader 2019.010.20098. 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 the value property of a Field object within AcroForms. 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 in conjunction with other vulnerabilities to execute code in the context of the current process. Was ZDI-CAN-8230.
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Analysis
by VulDB Data Team • 09/26/2023
The vulnerability identified as CVE-2019-6771 represents a critical information disclosure flaw within Foxit Reader version 2019.010.20098 that exposes systems to remote exploitation through carefully crafted malicious content. This vulnerability specifically targets the AcroForms implementation within the PDF reader, where improper object validation leads to potential data leakage and system compromise. The flaw operates at the core of how the application handles Field objects within PDF forms, creating a pathway for attackers to extract sensitive information from vulnerable installations.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the Field object handling code. When processing the value property of AcroForms, the application fails to verify whether referenced objects actually exist before attempting operations on them. This absence of proper object existence checking creates a condition where attackers can manipulate form fields to trigger unintended behavior. The vulnerability manifests when the application attempts to access a non-existent object reference, potentially exposing memory contents or internal application state information. This type of flaw aligns with CWE-476 which specifically addresses NULL pointer dereference vulnerabilities, where applications fail to validate object references before use.
From an operational perspective, this vulnerability requires user interaction to be exploited successfully, making it a client-side attack vector that relies on social engineering techniques. An attacker must convince a user to visit a malicious webpage containing crafted PDF content or open a specially designed malicious file. Once executed, the vulnerability can potentially enable attackers to gather sensitive information about the target system, including memory addresses, application state data, or other confidential information that could aid in further exploitation attempts. The impact extends beyond simple information disclosure as this vulnerability can serve as a stepping stone for more sophisticated attacks, potentially leading to arbitrary code execution within the context of the running Foxit Reader process.
The security implications of CVE-2019-6771 align with several ATT&CK framework techniques including T1059 for execution through malicious documents and T1068 for privilege escalation via application exploitation. The vulnerability's classification as a remote code execution risk through information disclosure demonstrates how seemingly minor validation flaws can compound into serious security threats. Organizations running vulnerable versions of Foxit Reader face significant exposure risks, particularly in environments where users may encounter untrusted PDF content. The vulnerability's exploitation requires no specialized tools beyond basic web browsing capabilities, making it particularly dangerous in enterprise environments where user behavior cannot always be controlled. Security professionals should consider this vulnerability as part of broader exploitation chains that could lead to complete system compromise.
Mitigation strategies for CVE-2019-6771 should include immediate patching of Foxit Reader installations to the latest available versions that contain the necessary security fixes. Organizations should also implement strict content filtering measures for PDF files, particularly in high-risk environments where user interaction with untrusted content is possible. Network-level controls such as web application firewalls and content inspection systems can help detect and block malicious PDF content before it reaches end users. Additionally, user education programs should emphasize the dangers of opening suspicious PDF files or visiting untrusted websites that may contain malicious content. Regular security assessments and vulnerability scanning should be conducted to identify any remaining vulnerable installations within the organization's infrastructure, ensuring comprehensive protection against this and similar vulnerabilities.