CVE-2009-0166 in CUPS
Summary
by MITRE
The JBIG2 decoder in Xpdf 3.02pl2 and earlier, CUPS 1.3.9 and earlier, and other products allows remote attackers to cause a denial of service (crash) via a crafted PDF file that triggers a free of uninitialized memory.
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Analysis
by VulDB Data Team • 09/02/2019
The vulnerability identified as CVE-2009-0166 represents a critical memory safety issue affecting JBIG2 decoders implemented in several PDF processing applications including Xpdf version 3.02pl2 and earlier, and CUPS version 1.3.9 and earlier. This flaw manifests as a remote denial of service condition that can be triggered by maliciously crafted PDF files, making it particularly dangerous in environments where users might encounter untrusted documents. The vulnerability stems from improper memory management practices within the JBIG2 decoding component, which processes the JBIG2 image compression format commonly used in PDF documents.
The technical root cause of this vulnerability lies in the improper handling of memory allocation and deallocation processes within the JBIG2 decoder implementation. When processing a specially crafted PDF file containing malformed JBIG2 data, the decoder attempts to free memory that has not been properly initialized or allocated, leading to unpredictable behavior and ultimately causing the application to crash. This type of vulnerability falls under the CWE-415: Double Free category, although it specifically manifests as uninitialized memory access rather than a traditional double free scenario. The flaw demonstrates poor memory management practices that are consistent with memory safety issues commonly found in C and C++ based applications where developers fail to properly validate memory states before operations.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to systematically crash applications processing PDF documents. In enterprise environments where PDF handling is common, such as document management systems, web browsers, or print servers, this vulnerability could enable attackers to perform persistent denial of service attacks against critical infrastructure. The vulnerability affects not just individual user applications but also server-side processing systems that handle PDF document ingestion, potentially impacting print servers, document repositories, or content management systems that rely on these vulnerable libraries. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access to the target system, making it particularly dangerous in networked environments.
Mitigation strategies for this vulnerability should focus on immediate patching of affected software versions, as the primary solution involves updating to versions that contain proper memory management fixes for the JBIG2 decoder. Organizations should prioritize updating their Xpdf and CUPS installations to versions that address this specific memory handling issue. Additionally, implementing defensive measures such as PDF validation and sanitization before processing, along with network segmentation and access controls, can help reduce the attack surface. The vulnerability demonstrates the importance of proper input validation and memory management practices in security-critical components, aligning with ATT&CK technique T1499.004 for network denial of service attacks and highlighting the necessity of secure coding practices in multimedia processing libraries. Organizations should also consider implementing monitoring and alerting for application crashes or unexpected behavior when processing PDF documents, as these could indicate exploitation attempts.