CVE-2018-9937 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.0.29935. 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 parsing of subform elements. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code under the context of the current process. Was ZDI-CAN-5371.
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Analysis
by VulDB Data Team • 07/14/2024
The vulnerability identified as CVE-2018-9937 represents a critical security flaw in Foxit Reader version 9.0.0.29935 that enables remote code execution through a type confusion vulnerability in the PDF parsing engine. This vulnerability operates at the intersection of software security and exploit development, where improper input validation creates opportunities for malicious actors to gain unauthorized system access. The issue stems from the application's handling of subform elements within PDF documents, specifically during the parsing phase where the software fails to properly validate user-supplied data structures. This failure creates a condition where the application's memory management becomes compromised, allowing attackers to manipulate object types and execute arbitrary code with the privileges of the currently running process.
The technical nature of this vulnerability aligns with CWE-467, which describes "Use of sizeof() on a Pointer Type" and more specifically relates to type confusion issues that occur when the software incorrectly handles object types during runtime operations. The vulnerability operates under the ATT&CK framework's technique T1203, which involves exploitation of software vulnerabilities to gain remote access, and T1059, which covers command and scripting interpreter usage for execution. The type confusion condition manifests when the PDF parser encounters malformed subform elements that cause the application to misinterpret memory objects, leading to unpredictable behavior that attackers can exploit to redirect execution flow and inject malicious payloads.
From an operational perspective, this vulnerability presents significant risk to organizations relying on Foxit Reader for document processing, as it requires only a single interaction from a user to compromise the system. The attack vector involves either a malicious webpage that loads a specially crafted PDF or a direct file attachment that triggers the vulnerable parsing code path. Once executed, the exploit can establish persistent access, escalate privileges, or create backdoors within the target environment. The vulnerability's impact extends beyond individual user systems to potentially compromise entire network infrastructures, particularly in environments where PDF documents are frequently shared and opened by multiple users.
Mitigation strategies for CVE-2018-9937 should prioritize immediate patch deployment from Foxit Corporation, as the vendor has released updates addressing the specific type confusion vulnerability in the subform element parsing. Organizations should implement network-level controls such as web application firewalls and content filtering systems to block malicious PDF content from entering the network perimeter. Additionally, user education programs should emphasize the importance of avoiding untrusted PDF files and websites, while security teams should monitor for indicators of compromise related to this vulnerability. System hardening measures including restricted user permissions, application whitelisting, and sandboxing techniques can provide additional defense layers against exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and memory management practices in preventing type confusion attacks that can lead to complete system compromise.