CVE-2018-21238 in PhantomPDF
Summary
by MITRE
An issue was discovered in Foxit PhantomPDF before 8.3.7. It allows memory consumption via an ArrayBuffer(0xfffffffe) call.
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Analysis
by VulDB Data Team • 10/22/2020
The vulnerability identified as CVE-2018-21238 represents a critical memory consumption flaw in Foxit PhantomPDF software versions prior to 8.3.7. This issue stems from improper handling of memory allocation requests within the PDF rendering engine, specifically when processing ArrayBuffer operations. The flaw manifests when the application encounters a call to ArrayBuffer with a parameter value of 0xffffffff, which translates to approximately 4.3 billion bytes or 4GB of memory allocation request. This excessive memory allocation request occurs during PDF document processing and can be triggered through maliciously crafted PDF files or documents containing crafted ArrayBuffer calls.
The technical implementation of this vulnerability resides in the JavaScript engine component of Foxit PhantomPDF, which handles interactive PDF features and scripting capabilities. When the application processes a PDF document containing an ArrayBuffer(0xffffffff) call, it attempts to allocate an enormous amount of memory that far exceeds typical system capabilities. This behavior violates standard memory management practices and demonstrates a lack of proper input validation and boundary checking within the application's JavaScript engine. The vulnerability is classified as a memory exhaustion issue that can lead to denial of service conditions, application crashes, and potentially system instability. The flaw operates at the application layer and does not require elevated privileges to exploit, making it particularly dangerous in enterprise environments where PDF processing is common.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can compromise system stability and availability across multiple platforms. When exploited, the vulnerability forces the PDF viewer to consume excessive memory resources, potentially leading to system slowdowns, application hangs, or complete system crashes. In enterprise environments, this could result in significant productivity losses and increased IT support burden, especially when users encounter malicious PDF documents during routine operations. The vulnerability affects all versions of Foxit PhantomPDF before 8.3.7 and represents a failure in proper resource management and input sanitization within the PDF rendering pipeline. Organizations using older versions of the software face increased risk of service disruption and potential compromise of their document processing workflows.
Mitigation strategies for this vulnerability center on immediate software updates to Foxit PhantomPDF version 8.3.7 or later, which contain patched implementations of the JavaScript engine with proper memory allocation validation. System administrators should prioritize deployment of this security update across all affected endpoints, particularly in environments where PDF processing is frequent and critical to operations. Additional protective measures include implementing PDF file scanning and filtering mechanisms at network boundaries, disabling JavaScript execution in PDF viewers where possible, and establishing monitoring protocols to detect unusual memory consumption patterns. From a cybersecurity perspective, this vulnerability aligns with attack techniques categorized under the ATT&CK framework as privilege escalation and denial of service tactics, specifically targeting application stability through resource exhaustion. Organizations should also consider implementing sandboxing technologies for PDF processing and maintaining regular vulnerability assessments to identify similar memory management flaws in other PDF viewing applications. The vulnerability demonstrates the importance of proper input validation and resource management practices, aligning with CWE categories related to memory allocation errors and insufficient resource management in software applications.