CVE-2018-9939 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 handling of layout 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-5373.
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Analysis
by VulDB Data Team • 07/14/2024
The vulnerability identified as CVE-2018-9939 represents a critical security flaw in Foxit Reader version 9.0.0.29935 that enables remote code execution through a type confusion vulnerability. This issue falls under the CWE-476 category of NULL Pointer Dereference, though the specific manifestation involves type confusion that occurs during the processing of layout elements within the PDF rendering engine. The vulnerability requires user interaction to be exploited, meaning that an attacker must convince a victim to visit a malicious webpage or open a specially crafted malicious file containing the exploit. This attack vector aligns with the ATT&CK technique T1203 - Exploitation for Client Execution, which specifically targets applications that process user-supplied content.
The technical root cause of this vulnerability stems from inadequate input validation within the PDF parser's handling of layout elements. When Foxit Reader processes a PDF document containing malformed or maliciously constructed layout data, the application fails to properly validate the type information associated with various data structures. This type confusion condition allows an attacker to manipulate the memory layout of the application by providing crafted input that tricks the parser into treating data of one type as another. The vulnerability occurs during the parsing phase when the application attempts to process layout elements without sufficient type checking, enabling an attacker to overwrite critical memory locations or manipulate execution flow. This type confusion vulnerability specifically affects the application's ability to maintain proper type safety during object manipulation, creating a pathway for arbitrary code execution.
The operational impact of CVE-2018-9939 is severe, as successful exploitation allows attackers to execute arbitrary code with the privileges of the currently running Foxit Reader process. This means that if a user opens a malicious PDF file, the attacker gains the ability to perform actions such as installing malware, modifying system files, accessing sensitive data, or establishing persistence mechanisms within the victim's environment. The vulnerability's remote exploitability makes it particularly dangerous for organizations, as attackers can deliver malicious payloads through email attachments, web downloads, or compromised websites. The fact that the vulnerability requires user interaction but can be delivered remotely through web-based attacks makes it a prime target for phishing campaigns and drive-by download attacks, which are common vectors in enterprise security breaches.
Organizations should implement immediate mitigations including updating Foxit Reader to versions that address this vulnerability, typically those released after the patching of CVE-2018-9939. System administrators should also consider implementing network-based protections such as web application firewalls and content filtering solutions to block access to known malicious domains. Additionally, user education programs should emphasize the importance of not opening unexpected email attachments or visiting untrusted websites. The vulnerability demonstrates the critical importance of input validation and type safety in security-critical applications, particularly those that process untrusted data such as PDF documents. Security teams should also monitor for indicators of compromise related to this vulnerability, including unusual network connections or file modifications that might indicate successful exploitation attempts. The remediation approach should also include regular security assessments of document processing applications and implementation of defense-in-depth strategies that reduce the attack surface and limit the potential impact of similar vulnerabilities.