CVE-2016-4060 in Foxit
Summary
by MITRE
Use-after-free vulnerability in Foxit Reader and PhantomPDF before 7.3.4 on Windows allows remote attackers to cause a denial of service (application crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 10/21/2018
The CVE-2016-4060 vulnerability represents a critical use-after-free flaw affecting Foxit Reader and PhantomPDF versions prior to 7.3.4 on Windows operating systems. This vulnerability falls under the category of memory safety issues and specifically manifests as a use-after-free condition that can be exploited remotely by attackers. The flaw occurs when the affected applications handle certain PDF objects or resources in a manner that leaves memory regions accessible after they have been freed, creating opportunities for malicious code execution or system instability. The vulnerability is particularly concerning because it allows remote attackers to trigger application crashes without requiring local system access or user interaction beyond opening a maliciously crafted PDF file. Such remote exploitation capabilities make this vulnerability especially dangerous in enterprise environments where users may encounter untrusted PDF content from various sources including email attachments, web downloads, or document sharing platforms.
The technical implementation of this use-after-free vulnerability stems from improper memory management within the PDF processing components of these applications. When parsing specific PDF structures or handling certain embedded objects, the software fails to properly validate object lifecycles, leading to scenarios where pointers reference memory that has already been deallocated. This condition typically arises during the processing of malformed or specially crafted PDF content that includes unusual object references or complex embedded elements. The vulnerability can be triggered through various PDF elements such as JavaScript actions, embedded files, or malformed object structures that cause the application to access freed memory regions. According to CWE classification, this vulnerability maps to CWE-416 which specifically addresses the use of freed memory conditions, making it a direct implementation of memory safety violations that have been consistently identified as high-risk security flaws in software applications. The flaw is particularly dangerous because it can be leveraged to cause denial of service attacks that render the application completely unusable, effectively preventing legitimate users from accessing PDF documents.
The operational impact of CVE-2016-4060 extends beyond simple application crashes to encompass potential system compromise and business disruption in enterprise environments. Organizations that rely heavily on PDF document processing face significant risks when this vulnerability exists in their software ecosystem, as attackers can exploit it to disrupt critical business operations or potentially escalate privileges through more sophisticated attack chains. The vulnerability's remote exploitability means that threat actors can target users without requiring physical access to systems, making it particularly attractive for widespread attacks. In the context of ATT&CK framework, this vulnerability aligns with techniques such as T1203 (Exploitation for Client Execution) and T1499 (Endpoint Denial of Service) where attackers leverage application flaws to achieve system disruption or compromise. The vulnerability's impact is amplified in environments where users frequently open PDF documents from untrusted sources, including email systems, web portals, and document sharing services. Organizations may experience significant downtime as users report application crashes, and IT departments must allocate resources to patch affected systems and potentially investigate potential compromise indicators.
Mitigation strategies for CVE-2016-4060 primarily focus on immediate software updates and deployment of patches provided by Foxit Corporation. The most effective solution involves upgrading to Foxit Reader and PhantomPDF version 7.3.4 or later, which includes memory management fixes that address the use-after-free condition. System administrators should implement comprehensive patch management processes to ensure all affected applications are updated across the enterprise environment. Additional protective measures include implementing PDF content filtering solutions that scan and sanitize PDF files before they reach end users, deploying application whitelisting policies to restrict execution of untrusted PDF viewers, and configuring sandboxing environments for PDF processing. Network-level protections such as email filtering and web proxy configurations can help prevent users from accessing potentially malicious PDF content. Organizations should also consider implementing security awareness training programs to educate users about the risks of opening untrusted PDF documents. The vulnerability highlights the importance of regular security assessments and vulnerability management programs, as use-after-free conditions often represent the result of insufficient input validation and memory management practices. Given the ATT&CK framework's emphasis on defending against exploitation techniques, organizations should also consider implementing monitoring solutions that can detect unusual application behavior patterns that might indicate exploitation attempts. Regular security audits and penetration testing should include assessment of PDF processing components to identify similar memory safety vulnerabilities that could be exploited in similar attack vectors.