CVE-2019-6733 in PhantomPDF
Summary
by MITRE
This vulnerability allows remote attackers to disclose sensitive information on vulnerable installations of Foxit PhantomPDF. 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 PDF files. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated buffer. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process. Was ZDI-CAN-7576.
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Analysis
by VulDB Data Team • 08/04/2023
The CVE-2019-6733 vulnerability represents a critical buffer over-read flaw in Foxit PhantomPDF software that demonstrates the dangers of inadequate input validation in document processing applications. This vulnerability resides within the PDF file handling mechanisms of the software, specifically when processing malformed or maliciously crafted PDF content. The flaw manifests as improper validation of user-supplied data during PDF parsing operations, creating a scenario where the application reads beyond the boundaries of allocated memory buffers. The vulnerability requires user interaction to be exploited effectively, meaning that an attacker must convince a target to visit a malicious webpage or open a specially crafted PDF file. This user interaction requirement aligns with common attack vectors in the cybersecurity landscape where social engineering plays a crucial role in initial compromise. The vulnerability is categorized under CWE-125 as an out-of-bounds read, which represents one of the most prevalent and dangerous classes of memory corruption vulnerabilities. When exploited, this flaw can potentially allow attackers to access sensitive information stored in memory, including credentials, personal data, or other confidential content. The memory corruption aspect of this vulnerability also opens the door for more sophisticated attacks where the buffer over-read could be leveraged as a stepping stone to achieve arbitrary code execution. This type of vulnerability is particularly concerning in document processing software because these applications often handle untrusted content from multiple sources and operate with elevated privileges to process and render documents properly. The attack surface expands significantly when considering that PDF files can be embedded in various contexts such as email attachments, web pages, or file sharing systems, making the exploitation vector more diverse and accessible to threat actors. From an operational perspective, this vulnerability impacts organizations that rely on Foxit PhantomPDF for document management and processing, potentially exposing sensitive corporate data or personal information. The ZDI-CAN-7576 reference indicates this vulnerability was tracked by the Zero Day Initiative, highlighting its significance in the threat landscape and the need for prompt remediation. The memory corruption nature of the vulnerability places it within the ATT&CK framework under the technique of "Memory Injection" and "Exploitation for Privilege Escalation" when combined with other vulnerabilities. Organizations should implement immediate mitigations including disabling the PDF viewing functionality in web browsers, updating to patched versions of Foxit PhantomPDF, and deploying network-based intrusion detection systems to monitor for exploitation attempts. The vulnerability also underscores the importance of input validation and proper bounds checking in software development practices, particularly for applications handling untrusted data formats such as PDF documents. Security teams should also consider implementing application whitelisting policies and restricting user access to potentially malicious content through email filtering and web proxy configurations to reduce the attack surface and limit potential exploitation opportunities.