CVE-2016-4064 in Foxit
Summary
by MITRE
Use-after-free vulnerability in the XFA forms handling functionality in Foxit Reader and PhantomPDF before 7.3.4 on Windows allows remote attackers to execute arbitrary code via a crafted remerge call.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/21/2018
The vulnerability identified as CVE-2016-4064 represents a critical use-after-free flaw within the XFA forms processing component of Foxit Reader and PhantomPDF applications. This security weakness exists in versions prior to 7.3.4 on Windows operating systems, creating a significant attack surface that remote adversaries can exploit to achieve arbitrary code execution. The vulnerability specifically manifests within the handling of remerge calls within the XFA forms functionality, which is a sophisticated feature designed to manage complex form data merging operations. The flaw occurs when the application fails to properly validate or manage memory references during the processing of maliciously crafted XFA form data, leading to a situation where freed memory locations are accessed after being deallocated.
The technical implementation of this vulnerability stems from improper memory management practices within the XFA forms engine. When processing a specially crafted document containing a malicious remerge call, the application allocates memory for form processing but fails to adequately track or validate the memory state during subsequent operations. This memory management failure creates a use-after-free condition where an attacker can manipulate the application's memory layout to overwrite critical data structures or function pointers. The vulnerability is classified under CWE-416 as a Use After Free condition, which occurs when a program continues to reference memory after it has been freed, potentially allowing for memory corruption and code execution. The attack vector requires remote exploitation through a specially crafted PDF document, making it particularly dangerous as it can be delivered via email attachments, web downloads, or malicious websites without requiring user interaction beyond opening the document.
The operational impact of CVE-2016-4064 extends beyond simple privilege escalation or denial of service scenarios, as it enables full arbitrary code execution capabilities. Attackers leveraging this vulnerability can execute malicious code with the privileges of the targeted user, potentially leading to complete system compromise, data exfiltration, or deployment of additional malware. The vulnerability affects organizations using Foxit Reader and PhantomPDF versions prior to 7.3.4, which were widely deployed in enterprise environments for document processing and form management. This makes the attack surface particularly broad, as many organizations rely on these applications for critical business processes involving sensitive data handling. The exploitability of this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as successful exploitation would allow attackers to execute arbitrary commands on the compromised system. The memory corruption resulting from the use-after-free condition can be leveraged to overwrite return addresses, function pointers, or other critical program structures, enabling attackers to redirect execution flow and inject malicious payloads.
Organizations affected by this vulnerability should prioritize immediate remediation through patching to version 7.3.4 or later of Foxit Reader and PhantomPDF. The mitigation strategy involves not only updating the affected applications but also implementing additional security controls such as sandboxing PDF processing, restricting document downloads from untrusted sources, and deploying network-based intrusion detection systems to monitor for exploitation attempts. Security teams should also consider implementing application whitelisting policies to limit execution of potentially malicious code and conduct regular vulnerability assessments to identify similar memory management issues in other software components. The vulnerability demonstrates the importance of proper memory management practices and the need for thorough security testing of complex features like XFA forms processing. Organizations should also review their incident response procedures to ensure readiness for potential exploitation attempts and maintain up-to-date threat intelligence regarding similar vulnerabilities in PDF processing libraries and applications.