CVE-2017-16575 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 8.3.1.21155. 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's bind element. 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-5091.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-16575 represents a critical remote code execution vulnerability affecting Foxit Reader version 8.3.1.21155 that demonstrates a classic object validation flaw in the XFA (XML Forms Architecture) processing component. This vulnerability resides within the bind element of XFA forms, where the application fails to properly validate whether an object exists before attempting operations on it. The flaw constitutes a direct violation of secure coding principles and aligns with CWE-476, which specifically addresses null pointer dereference vulnerabilities. The vulnerability operates under the principle of uninitialized object access, where the application assumes object existence without proper validation, creating an exploitable condition that allows attackers to manipulate memory operations through crafted XFA forms.
The exploitation mechanism requires user interaction through either visiting a malicious webpage containing crafted XFA content or opening a malicious PDF file that triggers the vulnerable XFA processing code path. This user interaction requirement places the vulnerability in the category of client-side attacks that rely on social engineering tactics, making it particularly dangerous in enterprise environments where users may inadvertently encounter malicious content. The vulnerability's impact extends beyond simple code execution to full system compromise, as the attacker can execute arbitrary code under the privileges of the current process, which typically runs with the same permissions as the vulnerable application. This privilege escalation capability aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, and T1068, which addresses exploit for privilege escalation.
The technical implementation of this vulnerability demonstrates a fundamental flaw in the application's input validation and object lifecycle management within the XFA processing engine. When the bind element processes form data, it attempts to access objects without verifying their existence, creating a path where attacker-controlled data can manipulate the application's memory state. This flaw represents a classic buffer overflow condition in the context of modern application security, where improper validation allows memory corruption through controlled input. The vulnerability's exploitation potential is amplified by the fact that Foxit Reader's XFA processing is enabled by default, meaning that simply opening a malicious PDF file can trigger the exploit without requiring any special configuration or user consent beyond the initial file opening.
Organizations affected by this vulnerability face significant operational risks, as the combination of remote exploit capability and user interaction requirements creates multiple attack vectors that can be leveraged through phishing campaigns, malicious websites, or compromised content. The vulnerability's presence in a widely used PDF reader application means that successful exploitation can lead to complete system compromise, data exfiltration, and lateral movement within network environments. Security professionals should note that this vulnerability represents a critical risk to enterprise security postures, particularly in environments where PDF documents are frequently exchanged and where users may not be adequately trained to recognize potentially malicious content. The vulnerability's classification as a remote code execution flaw places it in the highest severity category, requiring immediate attention and remediation to prevent potential exploitation by threat actors. Mitigation strategies should include immediate patch deployment, user education regarding suspicious PDF content, and network-level controls to monitor and block malicious PDF file transfers.