CVE-2018-19208 in libwpd
Summary
by MITRE
In libwpd 0.10.2, there is a NULL pointer dereference in the function WP6ContentListener::defineTable in WP6ContentListener.cpp that will lead to a denial of service attack. This is related to WPXTable.h.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/05/2023
The vulnerability identified as CVE-2018-19208 represents a critical NULL pointer dereference flaw within the libwpd library version 0.10.2, specifically impacting the WP6ContentListener::defineTable function in WP6ContentListener.cpp. This issue stems from inadequate input validation and error handling mechanisms within the library's processing of WordPerfect document formats. The flaw manifests when the library attempts to process malformed or specially crafted WP6 files that contain table structures, leading to a scenario where a null pointer is dereferenced during table definition processing. This vulnerability is particularly concerning as it affects the core document parsing functionality of the library, which is widely used across various applications for handling WordPerfect document formats.
The technical nature of this vulnerability aligns with CWE-476, which categorizes NULL pointer dereferences as a common software weakness that can lead to application crashes and potential denial of service conditions. The flaw occurs within the WPXTable.h header file's interaction with the WP6ContentListener::defineTable function, indicating that the issue originates from improper handling of table-related data structures during document parsing. When an attacker crafts a malicious WordPerfect document containing malformed table definitions, the library fails to properly validate pointer references before dereferencing them, resulting in a segmentation fault or application crash. This behavior directly maps to the ATT&CK technique T1499.004, which involves denial of service through resource exhaustion or application crashes, as the vulnerability specifically targets the availability of applications relying on this library.
The operational impact of CVE-2018-19208 extends beyond simple application crashes to potentially compromise system availability and stability. Applications that utilize libwpd for document processing, including office suites, document conversion tools, and content management systems, become vulnerable to denial of service attacks when processing untrusted WordPerfect documents. Attackers can exploit this vulnerability by delivering maliciously crafted WP6 files that trigger the NULL pointer dereference during table processing, causing the affected applications to terminate unexpectedly or become unresponsive. The vulnerability is particularly dangerous in server environments or applications that automatically process user-uploaded documents, as it can be leveraged to systematically disrupt service availability. The flaw's exploitation requires minimal technical expertise, making it a preferred target for adversaries seeking to disrupt services without requiring advanced penetration testing skills.
Mitigation strategies for CVE-2018-19208 should focus on immediate library updates to version 0.10.3 or later, which contains the necessary patches addressing the NULL pointer dereference issue. System administrators and developers should implement input validation measures that filter or sanitize WordPerfect documents before processing them through libwpd, particularly when handling untrusted content. Additionally, deploying application-level sandboxing techniques can help isolate vulnerable applications and limit the potential impact of successful exploitation attempts. Organizations should also consider implementing network-level controls that restrict processing of potentially malicious documents, especially in environments where automatic document conversion is enabled. The vulnerability underscores the importance of maintaining up-to-date third-party libraries and implementing robust error handling mechanisms that prevent null pointer dereferences from causing system-wide disruptions. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other dependencies that may be susceptible to analogous denial of service conditions.