CVE-2018-17668 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 handling of the removeAttribute method of a XFA object. 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-6522.
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Analysis
by VulDB Data Team • 05/05/2020
CVE-2018-17668 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.2.0.9297, classified under CWE-476 as "NULL Pointer Dereference" and aligning with ATT&CK technique T1203 for Exploitation for Client Execution. This vulnerability resides within the XFA (XML Forms Architecture) object handling mechanism, specifically in the removeAttribute method implementation where proper object validation is absent. The flaw manifests when the application attempts to perform operations on an object without first verifying its existence, creating a dangerous condition where a null pointer dereference can occur. This vulnerability operates at the intersection of memory safety and input validation, making it particularly dangerous for exploitation.
The attack vector requires user interaction, meaning a victim must either visit a malicious webpage or open a specially crafted malicious file containing the vulnerable XFA object. This makes the vulnerability susceptible to social engineering campaigns and phishing attacks, where attackers craft deceptive content to lure users into triggering the exploit. When the vulnerable Foxit Reader processes the malicious XFA object, the application's failure to validate object existence before invoking removeAttribute results in a crash or potentially allows for arbitrary code execution within the context of the current process. The exploitation leverages the application's trust in the structure of XFA forms without sufficient validation checks.
From an operational impact perspective, this vulnerability presents a significant risk to organizations relying on Foxit Reader for document processing, as successful exploitation could lead to complete system compromise. The vulnerability allows attackers to execute code with the privileges of the Foxit Reader process, potentially enabling lateral movement, data exfiltration, or persistence mechanisms. The attack surface expands when considering that Foxit Reader is widely used for processing PDF documents in enterprise environments, making this vulnerability particularly attractive to threat actors. The ZDI-CAN-6522 reference indicates this vulnerability was tracked by the Zero Day Initiative, highlighting its significance in the cybersecurity community.
Mitigation strategies should focus on immediate patching of Foxit Reader to version 9.2.1.9302 or later, which contains the necessary fixes for the XFA object validation issue. Organizations should also implement network-based protections such as web application firewalls and content filtering to prevent access to malicious content. Additionally, user education and awareness programs should be strengthened to reduce the likelihood of successful social engineering attacks. Security teams should monitor for indicators of compromise related to this vulnerability and consider implementing sandboxing techniques for PDF processing. The vulnerability demonstrates the importance of input validation in document processing applications and highlights the need for robust defensive measures against similar issues in other PDF rendering engines.