CVE-2017-7379 in PoDoFo
Summary
by MITRE
The PoDoFo::PdfSimpleEncoding::ConvertToEncoding function in PdfEncoding.cpp in PoDoFo 0.9.5 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via a crafted PDF document.
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Analysis
by VulDB Data Team • 08/25/2020
The vulnerability identified as CVE-2017-7379 resides within the PoDoFo library version 0.9.5, specifically in the PdfSimpleEncoding::ConvertToEncoding function located in PdfEncoding.cpp. This flaw represents a heap-based buffer over-read condition that can be exploited by remote attackers through the careful crafting of malicious PDF documents. The issue manifests when the library processes encoded character data without proper bounds checking, leading to memory access violations that result in application crashes and denial of service conditions. The vulnerability stems from inadequate input validation mechanisms within the PDF encoding conversion process, where the software fails to verify the integrity and size limitations of incoming encoded data before attempting to process it.
The technical exploitation of this vulnerability occurs when a malicious PDF document contains specially crafted encoding sequences that exceed the allocated buffer boundaries during the conversion process. The PdfSimpleEncoding::ConvertToEncoding function does not perform sufficient boundary checks to ensure that the input data fits within the expected memory allocation, creating a scenario where memory reads extend beyond the allocated heap space. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, specifically manifesting as a buffer over-read condition that can be leveraged for remote code execution or denial of service attacks. The attack vector requires no authentication and can be initiated through standard PDF document processing, making it particularly dangerous in environments where PDF files are automatically processed or opened.
The operational impact of CVE-2017-7379 extends beyond simple application crashes, potentially affecting systems that rely on PoDoFo for PDF manipulation and processing. Organizations using affected versions of PoDoFo in web applications, document processing systems, or automated PDF handling workflows face significant risk of service disruption and potential data exposure. The vulnerability can be exploited across multiple platforms where PoDoFo is implemented, including web browsers, document management systems, and server-side PDF processing applications. Attackers can craft PDF documents that trigger the buffer over-read condition when opened or processed by vulnerable applications, leading to system instability and potential service unavailability. This vulnerability directly maps to the ATT&CK technique T1203, which involves exploiting weaknesses in software libraries to cause denial of service or system compromise.
Mitigation strategies for CVE-2017-7379 primarily involve upgrading to PoDoFo version 0.9.6 or later, which includes patched implementations of the PdfSimpleEncoding::ConvertToEncoding function with proper boundary checking mechanisms. Organizations should implement comprehensive patch management procedures to ensure all systems utilizing PoDoFo are updated promptly. Additionally, deploying input validation measures and sandboxing techniques can provide defense-in-depth protection against exploitation attempts. The fix typically involves implementing proper bounds checking before memory operations and ensuring that encoded character data is validated against expected size limitations. Security teams should also consider monitoring for suspicious PDF file patterns and implementing network-based intrusion detection systems that can identify potential exploitation attempts. Regular security assessments of PDF processing workflows and library dependencies are essential to prevent similar vulnerabilities from emerging in other software components.