CVE-2020-13809 in Foxit
Summary
by MITRE
An issue was discovered in Foxit Reader and PhantomPDF before 9.7.2. It allows resource consumption via long strings in the content stream.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/22/2020
The vulnerability identified as CVE-2020-13809 affects Foxit Reader and PhantomPDF software versions prior to 9.7.2, representing a significant resource consumption issue that can lead to system instability and potential denial of service conditions. This flaw resides within the handling of content streams in pdf documents, specifically when processing excessively long strings that exceed normal operational parameters. The vulnerability manifests when the software encounters malformed or unusually lengthy content stream data during pdf parsing operations, causing the application to consume excessive computational resources.
The technical implementation of this vulnerability stems from inadequate input validation and resource management within the pdf rendering engine of these applications. When processing pdf content streams containing extended string sequences, the affected software fails to implement proper bounds checking or memory allocation limits, leading to uncontrolled resource consumption. This behavior aligns with CWE-770, which addresses allocation of resources without proper limits, and CWE-400, which covers resource exhaustion vulnerabilities. The flaw essentially creates a condition where the pdf parser becomes vulnerable to malicious input that can cause memory allocation to spiral out of control, potentially leading to application crashes or system performance degradation.
From an operational perspective, this vulnerability presents a substantial risk to organizations relying on Foxit Reader or PhantomPDF for document processing and viewing. Attackers could exploit this weakness by crafting malicious pdf documents containing excessively long strings in content streams, which when opened by vulnerable applications would trigger resource exhaustion. The impact extends beyond simple application instability to potentially enable more sophisticated attacks such as denial of service against critical systems or exploitation for privilege escalation in certain environments. The vulnerability operates at the application layer and can be triggered through simple pdf file manipulation, making it particularly dangerous for environments where users frequently open pdf documents from untrusted sources. This aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion.
Organizations should prioritize immediate remediation by upgrading to Foxit Reader or PhantomPDF version 9.7.2 or later, which contains patches specifically addressing this resource consumption issue. Additional mitigations include implementing pdf document scanning and validation procedures, restricting pdf file uploads in web applications, and establishing network-based intrusion detection systems to monitor for suspicious pdf content patterns. Security teams should also consider implementing application whitelisting controls and user education programs to reduce exposure to potentially malicious pdf files. The vulnerability demonstrates the importance of proper input validation and resource management in pdf processing applications, as highlighted by industry standards that emphasize the need for bounded resource allocation and robust error handling in document processing software.