CVE-2018-6352 in PoDoFo
Summary
by MITRE
In PoDoFo 0.9.5, there is an Excessive Iteration in the PdfParser::ReadObjectsInternal function of base/PdfParser.cpp. Remote attackers could leverage this vulnerability to cause a denial of service through a crafted pdf file.
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Analysis
by VulDB Data Team • 12/30/2019
The vulnerability identified as CVE-2018-6352 affects PoDoFo version 0.9.5, specifically within the PdfParser::ReadObjectsInternal function located in base/PdfParser.cpp. This issue represents a classic denial of service vulnerability that arises from inadequate input validation and processing logic within the PDF parsing component. The flaw manifests when the parser encounters specially crafted PDF files that contain excessive iterative structures or malformed object references, leading to uncontrolled resource consumption during document parsing operations.
The technical nature of this vulnerability stems from insufficient bounds checking and iteration limits within the parser's object reading mechanism. When processing malformed PDF content, the PdfParser::ReadObjectsInternal function fails to properly terminate iterative loops or impose reasonable iteration limits, causing the application to consume excessive CPU cycles and memory resources. This behavior aligns with CWE-835, which addresses the issue of infinite loops or excessive iteration that can lead to denial of service conditions. The vulnerability specifically targets the parsing logic that handles PDF object structures, where recursive or nested object references can cause the parser to enter into prolonged processing states without proper termination conditions.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted PDF documents, particularly in environments where automated PDF handling occurs such as email servers, document management systems, or web applications accepting PDF uploads. Remote attackers can exploit this weakness by crafting malicious PDF files that trigger the excessive iteration behavior, potentially causing system resource exhaustion and service disruption. The impact extends beyond simple denial of service as it can lead to system instability, application crashes, or even complete system unavailability when multiple malicious documents are processed concurrently. This vulnerability directly maps to ATT&CK technique T1499.001, which covers network denial of service attacks, and represents a critical weakness in the application's defensive mechanisms against malformed input processing.
Mitigation strategies for CVE-2018-6352 should prioritize immediate software updates to versions that address the excessive iteration logic in the PDF parser component. Organizations should implement input validation measures that enforce reasonable iteration limits and object nesting depth constraints when processing PDF documents. Additionally, deploying sandboxing mechanisms and resource monitoring can help detect and prevent exploitation attempts before they cause significant system impact. The fix should include implementing proper bounds checking, establishing maximum iteration thresholds, and adding timeout mechanisms to prevent indefinite processing of malformed PDF structures. Security teams should also consider implementing automated PDF analysis tools that can identify and quarantine suspicious document patterns before they reach the vulnerable parser component, ensuring comprehensive protection against this and similar input validation vulnerabilities.