CVE-2017-9865 in Poppler
Summary
by MITRE
The function GfxImageColorMap::getGray in GfxState.cc in Poppler 0.54.0 allows remote attackers to cause a denial of service (stack-based buffer over-read and application crash) via a crafted PDF document, related to missing color-map validation in ImageOutputDev.cc.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability identified as CVE-2017-9865 resides within the Poppler PDF rendering library version 0.54.0, specifically within the GfxImageColorMap::getGray function located in GfxState.cc. This flaw represents a critical security issue that enables remote attackers to execute denial of service attacks through carefully crafted malicious PDF documents. The vulnerability stems from inadequate validation mechanisms within the ImageOutputDev.cc component, which fails to properly validate color map parameters during PDF document processing. The attack vector exploits a stack-based buffer over-read condition that occurs when the application attempts to access memory beyond the allocated buffer boundaries during image color conversion operations.
The technical implementation of this vulnerability involves the improper handling of color mapping data within PDF image objects. When Poppler processes a PDF document containing specially constructed image data, the GfxImageColorMap::getGray function attempts to convert color values using a color map that has not been adequately validated. This validation gap allows an attacker to provide malformed color map parameters that exceed the expected buffer boundaries. The buffer over-read occurs because the function does not verify that the color map indices fall within valid ranges before accessing memory locations, leading to unpredictable memory access patterns that ultimately cause application crashes and system instability.
From an operational perspective, this vulnerability poses significant risks to systems that process untrusted PDF documents, including web browsers, email clients, and document management systems that utilize Poppler for PDF rendering. The denial of service impact extends beyond simple application crashes to potentially disrupt entire document processing workflows and user experiences. Security researchers have classified this as a stack-based buffer over-read vulnerability, which aligns with CWE-121, indicating a weakness in the program's memory management where data is read from memory locations beyond the bounds of a buffer. The vulnerability's remote exploitability means that attackers can trigger the condition without requiring local access to the target system, making it particularly dangerous in web-based environments where users may unknowingly encounter malicious PDF content.
The mitigation strategies for CVE-2017-9865 involve immediate patching of affected Poppler installations to versions that include proper color map validation. System administrators should also implement defensive measures such as PDF document sanitization and validation before processing, which aligns with ATT&CK technique T1074.201 for data staging and T1566.001 for spearphishing attachments. Organizations utilizing Poppler libraries should conduct comprehensive security assessments of their document processing pipelines and consider implementing sandboxing mechanisms to isolate PDF rendering operations. Additionally, network-level controls such as PDF content filtering and deep packet inspection can help prevent exploitation attempts. The vulnerability demonstrates the importance of proper input validation in graphics processing libraries and highlights the need for comprehensive testing of rendering components against malformed input data to prevent similar issues in the future.