CVE-2021-38565 in Foxit
Summary
by MITRE • 08/12/2021
An issue was discovered in Foxit PDF Reader before 11.0.1 and PDF Editor before 11.0.1. It allows writing to arbitrary files via submitForm.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2021-38565 represents a critical file system manipulation flaw affecting Foxit PDF Reader and PDF Editor versions prior to 11.0.1. This security defect enables malicious actors to exploit the submitForm functionality to write data to arbitrary file locations on the target system. The issue stems from insufficient input validation and improper access controls within the form submission mechanism, creating a path for unauthorized file operations that can be leveraged for various malicious purposes including privilege escalation, data exfiltration, or system compromise.
The technical root cause of this vulnerability lies in the improper handling of form submission parameters within the Foxit PDF processing engine. When users interact with certain form elements in PDF documents, the submitForm function fails to properly validate the destination paths specified in the form data. This allows attackers to craft malicious PDF documents containing form fields that, when submitted, can write content to arbitrary locations on the victim's file system. The flaw operates at the application layer and can be triggered through normal PDF document processing without requiring special privileges or elevated access rights.
From an operational perspective, this vulnerability poses significant risks to enterprise environments and individual users alike. Attackers can exploit this flaw by distributing malicious PDF documents through phishing campaigns, social engineering tactics, or compromised websites. The impact extends beyond simple file corruption as adversaries can leverage this capability to install malware, modify system files, or create backdoors within the victim's environment. The vulnerability is particularly concerning because it can be triggered automatically when PDF documents are opened, making it difficult for users to detect or prevent the malicious activity.
Security researchers have classified this vulnerability under CWE-22 which describes "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript'. The vulnerability demonstrates characteristics of privilege escalation and persistence mechanisms that attackers can utilize to establish long-term access to compromised systems. Organizations should consider implementing network-based protections such as PDF content filtering and sandboxing solutions to mitigate the risk of exploitation while awaiting vendor patches.
Mitigation strategies should include immediate deployment of Foxit's official security updates to version 11.0.1 or later, which address the improper input validation in the submitForm functionality. Network administrators should also implement strict PDF document inspection policies and consider deploying sandboxed environments for PDF processing. Additionally, user education regarding suspicious PDF documents and enabling automatic updates for PDF readers can significantly reduce the attack surface. The vulnerability underscores the importance of proper input validation and access control mechanisms in document processing applications, particularly those handling user-generated content and interactive elements such as forms.