CVE-2017-5854 in PoDoFo
Summary
by MITRE
base/PdfOutputStream.cpp in PoDoFo 0.9.4 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted file.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2017-5854 resides within the base/PdfOutputStream.cpp component of the PoDoFo library version 0.9.4, representing a critical security flaw that enables remote attackers to execute denial of service attacks through carefully crafted malicious PDF files. This issue manifests as a NULL pointer dereference condition that ultimately leads to application crashes, effectively disrupting normal operational procedures for systems relying on PoDoFo for PDF processing.
The technical root cause of this vulnerability stems from insufficient input validation within the PdfOutputStream.cpp module, where the application fails to properly handle malformed or specially constructed PDF elements during the output stream processing phase. When a malicious PDF file containing crafted data structures is processed by PoDoFo, the library attempts to dereference a NULL pointer without proper null checks, resulting in an immediate application termination. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a classic example of improper input validation leading to system instability.
From an operational perspective, this vulnerability presents significant risks to organizations that utilize PoDoFo for PDF handling in their applications, particularly those exposed to untrusted PDF content such as web applications, document processing services, or email systems. The remote exploitability means that attackers can trigger the denial of service condition without requiring local access or authentication, making it particularly dangerous in environments where PDF files are automatically processed. The impact extends beyond simple service disruption as it can affect business continuity, particularly in scenarios where PDF processing is critical to core operations such as document management systems, online portals, or automated workflow processes.
The attack surface for this vulnerability is extensive given PoDoFo's widespread use in various applications and systems that process PDF documents. Organizations implementing PoDoFo for PDF generation, manipulation, or viewing functions are at risk, especially those that do not properly sanitize input PDF files before processing. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks, and more specifically demonstrates how improper input validation can lead to system instability and service interruption. The vulnerability also represents a failure in defensive programming practices that should include proper null pointer checks and input sanitization mechanisms.
Mitigation strategies for CVE-2017-5854 should prioritize immediate patching of affected PoDoFo installations to version 0.9.5 or later, which contains the necessary fixes for this NULL pointer dereference issue. Additionally, organizations should implement proper input validation and sanitization measures for all PDF files processed by systems utilizing PoDoFo, including the implementation of robust error handling mechanisms that can gracefully handle malformed input without crashing. Network segmentation and access controls should be reviewed to limit exposure to potentially malicious PDF files, while application-level sandboxing techniques can provide additional protection layers. Regular security assessments and vulnerability scanning should be conducted to identify other potential instances of similar issues within the application stack, ensuring comprehensive protection against similar denial of service vulnerabilities.