CVE-2019-7233 in libdoc
Summary
by MITRE
In libdoc through 2019-01-28, doc2text in catdoc.c has a NULL pointer dereference.
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Analysis
by VulDB Data Team • 05/07/2020
The vulnerability identified as CVE-2019-7233 affects the libdoc library version released on or before January 28, 2019, specifically within the doc2text functionality located in the catdoc.c source file. This issue represents a critical null pointer dereference flaw that can lead to application crashes and potential denial of service conditions. The vulnerability manifests when the doc2text function processes certain input documents, particularly those containing malformed or improperly structured data that causes the function to attempt dereferencing a null pointer reference. Such behavior violates fundamental memory safety principles and can be exploited by malicious actors to disrupt service availability.
The technical nature of this vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations. This weakness occurs when a program attempts to access memory through a pointer that has not been properly initialized or validated, resulting in an abrupt program termination. The flaw exists within the document processing pipeline of libdoc, where the catdoc.c component fails to adequately validate input parameters before attempting to dereference pointers that may remain uninitialized or set to null values during document conversion operations. The attack surface is particularly concerning as it involves document parsing functionality that is commonly exposed in file processing applications, web services, and office automation systems.
Operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors. When exploited, the null pointer dereference can cause applications utilizing libdoc to crash repeatedly, leading to denial of service conditions that affect legitimate users and system availability. Attackers can craft malicious documents that trigger this condition, causing cascading failures in systems that depend on document conversion capabilities. The vulnerability is particularly dangerous in environments where automated document processing occurs, such as email servers, document management systems, or web applications that accept and process user-uploaded office documents. Security professionals should note that this flaw can be leveraged in combination with other vulnerabilities to create more complex attack scenarios, though it primarily functions as a denial of service mechanism.
Mitigation strategies for CVE-2019-7233 should prioritize immediate patching of affected libdoc versions to the latest stable release that contains the fix for the null pointer dereference issue. System administrators should implement input validation controls that sanitize all document inputs before processing, particularly focusing on document format detection and proper error handling. The implementation of defensive programming practices including pointer validation checks and proper error recovery mechanisms can help prevent exploitation of similar null pointer dereference vulnerabilities. Additionally, deployment of network-based intrusion detection systems that monitor for suspicious document processing activities may provide early warning of attempted exploitation. Organizations should also consider implementing application sandboxing or containerization techniques to limit the impact of potential exploitation, while maintaining regular vulnerability assessments to identify and remediate similar issues across their software portfolio. The ATT&CK framework categorizes this type of vulnerability under software vulnerabilities and specifically relates to privilege escalation and denial of service tactics that attackers may employ in broader exploitation campaigns.