CVE-2018-17681 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.2.0.9297. 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 getPageBox method of a Form. 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 in the context of the current process. Was ZDI-CAN-7141.
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Analysis
by VulDB Data Team • 07/31/2024
CVE-2018-17681 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297 that demonstrates a classic null pointer dereference flaw within the PDF processing engine. This vulnerability resides in the Form object handling mechanism, specifically within the getPageBox method implementation where insufficient input validation leads to improper object state management. The flaw manifests when the application attempts to perform operations on a Form object without first verifying its existence or proper initialization, creating a predictable exploitation vector for remote attackers. The vulnerability operates under CWE-476 which categorizes null pointer dereference conditions as a fundamental weakness in software design that can lead to arbitrary code execution when exploited properly.
The technical exploitation of this vulnerability requires a remote attacker to craft a malicious PDF document containing specially crafted Form elements that trigger the vulnerable getPageBox method. When a victim user opens this malicious file within Foxit Reader, the application's PDF parser processes the Form object and attempts to access memory locations through an uninitialized or improperly validated object reference. This memory access violation allows attackers to inject and execute arbitrary code within the context of the Foxit Reader process, potentially leading to complete system compromise. The attack vector requires user interaction through opening the malicious file, making it a client-side exploit that aligns with ATT&CK technique T1203 for exploitation for persistence.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the ability to escalate privileges within the application's security boundaries and potentially gain access to sensitive user data or system resources. The vulnerability's exploitation occurs within the PDF rendering context, meaning that successful attacks could result in unauthorized access to documents, system files, or network resources accessible to the Foxit Reader application. The lack of proper object validation in the Form processing module creates a persistent threat that can be leveraged for various malicious activities including data exfiltration, system reconnaissance, or further attack escalation. Organizations using Foxit Reader 9.2.0.9297 should consider this vulnerability as a high-priority risk due to its remote exploitability and the potential for privilege escalation within the application's execution environment.
Mitigation strategies for CVE-2018-17681 primarily focus on immediate software updates and administrative controls to reduce attack surface. The most effective solution involves upgrading Foxit Reader to version 9.2.1.9300 or later, which includes patches addressing the object validation issue in the Form handling mechanism. Additionally, organizations should implement strict PDF file access controls, including sandboxing mechanisms and content filtering solutions that can detect and block malicious PDF documents before they reach end users. Network-level protections such as web application firewalls and email security solutions should be configured to inspect PDF content and prevent delivery of potentially malicious documents. Administrative users should also consider implementing user access restrictions and monitoring for unusual PDF processing activities that might indicate exploitation attempts. The vulnerability's classification as a remote code execution flaw underscores the importance of maintaining current software patches and implementing defense-in-depth strategies to protect against similar weaknesses in other PDF processing applications.