CVE-2018-5309 in PoDoFo
Summary
by MITRE
In PoDoFo 0.9.5, there is an integer overflow in the PdfObjectStreamParserObject::ReadObjectsFromStream function (base/PdfObjectStreamParserObject.cpp). Remote attackers could leverage this vulnerability to cause a denial-of-service via a crafted pdf file.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/26/2020
The vulnerability identified as CVE-2018-5309 represents a critical integer overflow flaw within the PoDoFo document processing library version 0.9.5. This issue manifests specifically within the PdfObjectStreamParserObject::ReadObjectsFromStream function located in the base/PdfObjectStreamParserObject.cpp source file. The flaw occurs when processing PDF files that contain specially crafted object stream data, creating a scenario where an attacker can manipulate the parsing logic to trigger unexpected behavior in the library's memory management systems. The integer overflow vulnerability stems from inadequate input validation and bounds checking during the parsing of object stream data, which allows maliciously constructed PDF documents to cause the application to misinterpret data sizes and subsequently allocate insufficient memory for processing operations.
From a technical perspective, this vulnerability operates at the intersection of memory safety and input validation failures, classified under CWE-190 as an integer overflow error. The flaw enables remote attackers to construct malicious PDF files that, when processed by applications using PoDoFo 0.9.5, will trigger the overflow condition during object stream parsing. The vulnerability specifically affects the library's ability to correctly calculate and allocate memory for object data structures, leading to potential memory corruption or allocation failures that result in application instability. When the integer overflow occurs, it typically causes the parsing function to either allocate insufficient memory for the intended data structure or to perform operations using incorrect calculated values, ultimately leading to program termination or denial-of-service conditions.
The operational impact of CVE-2018-5309 extends beyond simple denial-of-service scenarios to potentially compromise the availability of PDF processing applications that depend on PoDoFo 0.9.5. Systems utilizing this library for PDF document handling, including web applications, document management systems, and security scanning tools, become vulnerable to attacks that can disrupt service availability. Attackers can exploit this vulnerability by preparing malicious PDF files that contain crafted object stream data designed to trigger the integer overflow condition. The attack requires no special privileges or authentication, making it particularly dangerous in environments where PDF files are automatically processed or where users can upload documents to systems using vulnerable libraries. This vulnerability aligns with ATT&CK technique T1203, which covers the use of malicious files to gain access to systems, as the crafted PDF files can be used to disrupt services and potentially provide a foothold for further exploitation.
Organizations using PoDoFo 0.9.5 should immediately implement mitigations to address CVE-2018-5309. The primary recommendation involves upgrading to a patched version of the PoDoFo library where the integer overflow has been corrected through proper input validation and bounds checking mechanisms. Additionally, implementing input sanitization measures at the application level can provide defense-in-depth protection, including validating PDF file structures before processing and implementing timeouts for PDF parsing operations. Network-level controls such as PDF file filtering and sandboxing mechanisms can further reduce the risk of exploitation by preventing potentially malicious PDF files from reaching vulnerable applications. The vulnerability demonstrates the importance of regular security updates and the critical need for proper integer handling in memory-sensitive applications, particularly those processing untrusted document formats like PDF files.