CVE-2017-9433 in libmwaw
Summary
by MITRE
Document Liberation Project libmwaw before 2017-04-08 has an out-of-bounds write caused by a heap-based buffer overflow related to the MsWrd1Parser::readFootnoteCorrespondance function in lib/MsWrd1Parser.cxx.
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Analysis
by VulDB Data Team • 10/13/2019
The Document Liberation Project libmwaw library contains a critical heap-based buffer overflow vulnerability that affects versions prior to 2017-04-08. This vulnerability manifests within the MsWrd1Parser::readFootnoteCorrespondance function located in the lib/MsWrd1Parser.cxx source file, representing a classic out-of-bounds write condition that can be exploited to compromise system integrity. The flaw occurs when processing Microsoft Word documents that contain specific footnote correspondence data structures, where insufficient input validation leads to memory corruption beyond allocated buffer boundaries.
This vulnerability falls under CWE-121 Heap-based Buffer Overflow, which is classified as a serious memory safety issue that allows attackers to write data beyond the bounds of allocated memory regions. The technical implementation involves the MsWrd1Parser class failing to properly validate the size of footnote correspondence data before attempting to write to heap-allocated memory structures. When malformed or maliciously crafted footnote data is encountered, the parser does not perform adequate bounds checking, resulting in a write operation that overflows the intended buffer and potentially corrupts adjacent memory regions.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can be leveraged for arbitrary code execution within the context of applications that utilize libmwaw for document processing. Attackers can craft specially formatted Microsoft Word documents that trigger the buffer overflow when opened or processed by vulnerable applications, potentially allowing for privilege escalation or complete system compromise. The vulnerability represents a significant risk in environments where users frequently open untrusted Word documents, particularly in enterprise settings where document processing libraries are commonly integrated into various applications and services.
Mitigation strategies for this vulnerability include immediate upgrading to libmwaw version 2017-04-08 or later, which contains the necessary patches to address the buffer overflow condition. Organizations should also implement input validation measures and sandboxing techniques when processing untrusted document formats, particularly those that utilize the affected MsWrd1Parser functionality. Additionally, system administrators should monitor for any applications that depend on vulnerable versions of libmwaw and ensure proper patch management protocols are in place to prevent exploitation attempts. The vulnerability demonstrates the importance of proper bounds checking in memory management operations and aligns with ATT&CK technique T1059.007 for execution through word processors, emphasizing the need for comprehensive security controls in document processing environments.