CVE-2018-5676 in Foxit Reader
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader before 9.1 and PhantomPDF before 9.1. 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 processing of specially crafted pdf files with embedded u3d images. Crafted data in the PDF file can trigger an overflow of a heap-based buffer. An attacker can leverage this vulnerability to execute code under the context of the current process, a different vulnerability than CVE-2018-5674 and CVE-2018-5678.
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Analysis
by VulDB Data Team • 02/08/2020
The vulnerability identified as CVE-2018-5676 represents a critical heap-based buffer overflow flaw affecting Foxit Reader versions prior to 9.1 and PhantomPDF versions prior to 9.1. This security weakness resides within the PDF processing engine's handling of embedded u3d (Universal 3D) images, which are three-dimensional graphics files commonly used in technical documentation and presentations. The flaw specifically manifests when the software encounters specially crafted PDF files containing maliciously formatted u3d content that triggers unauthorized memory manipulation. The vulnerability operates through a classic buffer overflow mechanism where insufficient bounds checking allows crafted data to overwrite adjacent memory locations, potentially leading to arbitrary code execution. This issue demonstrates the inherent risks associated with complex multimedia content processing within document viewers, particularly when dealing with 3D graphics formats that require extensive parsing and rendering capabilities.
The technical exploitation of CVE-2018-5676 requires user interaction to succeed, making it a client-side vulnerability that relies on social engineering tactics to deliver malicious payloads. Attackers must craft PDF documents containing embedded u3d images with specifically designed overflow patterns that cause the heap memory management to corrupt during processing. The vulnerability's exploitation path involves the PDF parser's handling of u3d data structures, where memory allocation occurs based on parsed header information that has been manipulated to exceed expected buffer boundaries. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a memory safety issue within the Common Weakness Enumeration framework. The attack surface is particularly concerning because it leverages legitimate PDF functionality while exploiting the underlying memory management implementation, making detection more challenging for traditional security controls that might not identify the malicious intent within otherwise valid PDF structures.
The operational impact of CVE-2018-5676 extends beyond simple code execution, as successful exploitation allows attackers to operate under the privileges of the currently running process, typically with the same user permissions as the vulnerable application. This means that if a user with administrative privileges opens a malicious PDF file, the attacker could potentially gain elevated system access. The vulnerability operates independently from other related issues such as CVE-2018-5674 and CVE-2018-5678, indicating that each flaw represents a distinct code path within the software's PDF processing capabilities. The threat landscape for this vulnerability includes targeted attacks against organizations that rely heavily on PDF document sharing, particularly in engineering, architectural, and technical documentation environments where 3D content is frequently embedded. The attack pattern aligns with the MITRE ATT&CK framework's technique T1203, which involves exploitation of software vulnerabilities for privilege escalation and system compromise. Organizations utilizing these vulnerable applications face significant risk as the exploitation requires minimal user interaction beyond opening a malicious document, making it particularly dangerous in phishing campaigns or targeted attacks.
Mitigation strategies for CVE-2018-5676 primarily focus on immediate software updates and application hardening measures. The most effective defense involves upgrading to Foxit Reader 9.1 or later versions and PhantomPDF 9.1 or later, which contain patches addressing the specific heap overflow conditions in u3d processing. System administrators should implement comprehensive patch management procedures to ensure all vulnerable applications are updated across the enterprise environment. Additional protective measures include configuring PDF viewers to disable embedded content processing, implementing strict file validation policies, and deploying network-based intrusion detection systems that can identify suspicious PDF file patterns. Organizations should also consider application whitelisting solutions that restrict execution of unauthorized PDF processing components and implement sandboxing techniques to isolate PDF rendering operations. The vulnerability's nature suggests that organizations should enhance their security awareness training programs to educate users about the risks of opening untrusted PDF files, particularly those containing embedded multimedia content. Security teams should monitor for indicators of compromise related to PDF-based attacks and maintain updated threat intelligence feeds to identify potential exploitation attempts targeting this specific vulnerability.