CVE-2019-15145 in DjVuLibre
Summary
by MITRE
DjVuLibre 3.5.27 allows attackers to cause a denial-of-service attack (application crash via an out-of-bounds read) by crafting a corrupted JB2 image file that is mishandled in JB2Dict::JB2Codec::get_direct_context in libdjvu/JB2Image.h because of a missing zero-bytes check in libdjvu/GBitmap.h.
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Analysis
by VulDB Data Team • 11/26/2023
The vulnerability CVE-2019-15145 represents a critical denial-of-service flaw in DjVuLibre version 3.5.27 that stems from improper input validation within the JB2 image processing subsystem. This vulnerability specifically affects the handling of corrupted JB2 image files, which are part of the DjVu document format used for storing and transmitting scanned documents and images. The flaw occurs when the application attempts to process malformed JB2 image data without adequate bounds checking, leading to an out-of-bounds memory read condition that ultimately causes the application to crash.
The technical root cause of this vulnerability lies in the JB2Dict::JB2Codec::get_direct_context function within the libdjvu/JB2Image.h library component. This function fails to perform proper zero-byte validation checks before processing image data, as mandated by CWE-129, which addresses insufficient bounds checking. The missing validation occurs in the libdjvu/GBitmap.h file where the application reads memory locations beyond the allocated buffer boundaries. When an attacker crafts a malicious JB2 image file with carefully constructed corrupted data, the application's failure to validate input parameters results in memory corruption that triggers a segmentation fault and subsequent application termination.
From an operational perspective, this vulnerability presents a significant risk to systems that process DjVu documents, particularly those in document management systems, digital libraries, or web applications that accept user-uploaded DjVu files. The attack requires minimal skill to execute as it only involves creating a specially crafted JB2 image file, making it accessible to threat actors with basic technical knowledge. The impact extends beyond simple service disruption to potentially enabling more sophisticated attacks if the application is part of a larger system where persistent denial-of-service conditions could be leveraged for further exploitation. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how seemingly benign file format processing can become a vector for system compromise.
The mitigation strategy for CVE-2019-15145 involves immediate patching of DjVuLibre to version 3.5.28 or later, which includes the necessary bounds checking mechanisms in both JB2Image.h and GBitmap.h components. Organizations should also implement input validation measures such as file format signature verification, size limitations, and sandboxing of document processing components. Additionally, network segmentation and access controls can limit the potential impact of successful exploitation attempts. Security monitoring should include detection of abnormal application termination patterns and file upload activities that could indicate exploitation attempts. The fix addresses the underlying CWE-129 vulnerability by implementing proper array bounds checking and zero-byte validation, ensuring that all memory access operations remain within allocated buffer boundaries. This vulnerability highlights the importance of robust input validation in multimedia processing libraries and demonstrates how seemingly isolated flaws can result in complete application compromise.