CVE-2019-9588 in Xpdf
Summary
by MITRE
There is an Invalid memory access in gAtomicIncrement() located at GMutex.h in Xpdf 4.01. It can be triggered by sending a crafted pdf file to (for example) the pdftops binary. It allows an attacker to cause Denial of Service (Segmentation fault) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 07/26/2023
The vulnerability identified as CVE-2019-9588 represents a critical memory access issue within the Xpdf library version 4.01, specifically within the gAtomicIncrement() function located in GMutex.h. This flaw manifests as an invalid memory access condition that can be exploited through the manipulation of PDF files, making it particularly dangerous in environments where PDF processing is common. The vulnerability affects the pdftops binary and other components that utilize the Xpdf library for PDF rendering and processing operations.
The technical nature of this vulnerability stems from improper memory handling within the atomic increment operation, which is fundamental to thread synchronization mechanisms. When a maliciously crafted PDF file is processed by applications using Xpdf, the gAtomicIncrement() function attempts to access memory locations that may not be properly allocated or accessible, leading to segmentation faults and system crashes. This memory access violation occurs during the processing of PDF documents, particularly when encountering specific malformed structures within the document that trigger the problematic code path.
From an operational impact perspective, this vulnerability creates significant risks for organizations relying on PDF processing capabilities. The primary consequence is denial of service, where legitimate PDF processing operations become disrupted due to segmentation faults that terminate applications abruptly. However, the potential for more severe impacts cannot be ruled out, as the invalid memory access could potentially be exploited to execute arbitrary code or cause further system instability. This makes the vulnerability particularly concerning for automated PDF processing systems, web applications, and document management platforms that handle untrusted PDF content.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of improper memory access patterns that can lead to system instability. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain targeting document processing systems, potentially enabling adversaries to disrupt services or establish persistent access through system compromise. The exploitation requires minimal privileges and can be executed through simple PDF file delivery, making it an attractive target for attackers seeking to disrupt operations.
Mitigation strategies should focus on immediate patching of the Xpdf library to version 4.02 or later, which contains the necessary fixes for this memory access issue. Organizations should also implement strict PDF file validation and sanitization processes before processing, particularly for untrusted content. Additionally, deploying application-level sandboxing and privilege separation mechanisms can help limit the potential impact of exploitation. Regular security assessments of PDF processing pipelines and monitoring for unusual application crashes or segmentation faults should be implemented as part of ongoing security operations to detect potential exploitation attempts.