CVE-2018-11617 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 Format events for ComboBox fields. 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 under the context of the current process. Was ZDI-CAN-5415.
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Analysis
by VulDB Data Team • 03/11/2020
The vulnerability identified as CVE-2018-11617 represents a critical remote code execution flaw in Foxit Reader version 9.0.0.29935 that demonstrates a classic object validation error pattern. This weakness resides within the PDF reader's handling of ComboBox field format events, where the application fails to properly validate whether an object exists before attempting operations on it. The vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is a fundamental programming error that occurs when software attempts to access a memory location through a null pointer reference. The flaw is particularly dangerous because it can be triggered through web-based attacks where users visit malicious pages or open compromised PDF files, making it a prime target for social engineering campaigns and drive-by download attacks.
The technical implementation of this vulnerability stems from improper input validation mechanisms within Foxit Reader's PDF parsing engine. When processing ComboBox fields in PDF documents, the application does not perform adequate checks to ensure that referenced objects are properly initialized before executing operations on them. This creates a condition where an attacker can craft a malicious PDF containing specially formatted ComboBox fields that, when processed by the vulnerable reader, trigger a null pointer dereference. The exploitation process typically involves creating a PDF document with malformed ComboBox field data that causes the reader to attempt operations on a non-existent object reference. The attacker can then leverage this condition to inject and execute arbitrary code within the context of the current process, effectively compromising the user's system.
The operational impact of CVE-2018-11617 extends beyond simple remote code execution, as it provides attackers with a persistent foothold in target systems. Since the vulnerability requires user interaction through visiting malicious web pages or opening compromised files, it aligns with the ATT&CK technique T1203 - Exploitation for Client Execution, which emphasizes the importance of user engagement in successful exploitation. The attack vector typically involves phishing campaigns, malicious websites, or compromised advertising networks that serve the malicious PDF files to unsuspecting users. Once exploited, the attacker gains the ability to execute code with the privileges of the Foxit Reader process, which may include full system access depending on the user's permissions and the system configuration. This vulnerability also demonstrates the broader risk associated with PDF reader applications, which often run with elevated privileges and have extensive access to system resources.
Mitigation strategies for CVE-2018-11617 should include immediate patching of Foxit Reader installations to version 9.0.1.1050 or later, which contains the necessary fixes for the object validation issue. Organizations should implement network-based protections such as web application firewalls and content filtering systems that can detect and block malicious PDF content. Additionally, user education and awareness programs should emphasize the importance of avoiding suspicious websites and email attachments, particularly those containing PDF files from unknown sources. The vulnerability also highlights the need for comprehensive application whitelisting policies that restrict execution of unauthorized software and limit the potential impact of such exploits. Security teams should monitor for indicators of compromise related to this vulnerability, including unusual network connections or file modifications that might indicate successful exploitation attempts. The remediation process should also include regular security assessments of PDF reader configurations and implementation of principle of least privilege concepts to minimize the damage that could result from successful exploitation of similar vulnerabilities.