CVE-2018-17628 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 XFA setInterval method. 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-6458.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17628 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297, demonstrating a classic null pointer dereference flaw that aligns with CWE-476. This vulnerability resides within the XFA (XML Forms Architecture) setInterval method, which is part of Adobe's XML-based form processing framework. The core technical flaw occurs when the application fails to validate whether an object exists before attempting operations on it, creating a dangerous condition where malicious input can trigger arbitrary code execution. This type of vulnerability falls under the ATT&CK technique T1059.007 for Command and Scripting Interpreter, specifically targeting the execution of malicious code through legitimate system processes.
The exploitation requires user interaction through either visiting a malicious webpage or opening a crafted malicious file, making this a prime example of a client-side attack vector that leverages social engineering tactics. When a user interacts with the malicious content, the XFA setInterval method processes the malformed input without proper validation checks, leading to a situation where an attacker-controlled pointer can be dereferenced, resulting in code execution within the context of the Foxit Reader process. This vulnerability essentially allows attackers to bypass normal security boundaries and execute arbitrary commands on the victim's system with the privileges of the Foxit Reader application.
The operational impact of this vulnerability is significant as it enables attackers to perform a wide range of malicious activities including data exfiltration, system compromise, and persistence mechanisms. The vulnerability's remote nature means that attackers can exploit it without requiring physical access to the target system, making it particularly dangerous in enterprise environments where users may inadvertently visit malicious websites or open compromised documents. The exploitation process typically involves crafting a malicious PDF document containing specially crafted XFA JavaScript that triggers the vulnerable code path. This vulnerability demonstrates the inherent risks of complex scripting engines within document processing applications and the critical importance of input validation in preventing such exploitation scenarios.
Organizations should implement multiple layers of defense to mitigate this vulnerability including immediate patching of affected Foxit Reader installations, network-based intrusion detection system rules to detect malicious PDF traffic, and user education programs to reduce the success rate of social engineering attacks. Security teams should also consider implementing application whitelisting policies that restrict execution of untrusted PDF files and monitor for unusual process behavior that might indicate exploitation attempts. The vulnerability's classification as a remote code execution flaw emphasizes the need for proactive security measures and regular vulnerability assessments to identify similar issues in other document processing applications. This case study highlights the importance of proper object validation in scripting environments and serves as a reminder that even seemingly benign functionality like setInterval methods can become attack vectors when proper input validation is absent.