CVE-2018-3981 in Word Processor
Summary
by MITRE
An exploitable uninitialized pointer vulnerability exists in the Word document parser of the the Atlantis Word Processor. A specially crafted document can cause an array fetch to return an uninitialized pointer and then performs some arithmetic before writing a value to the result. Usage of this uninitialized pointer can allow an attacker to corrupt heap memory resulting in code execution under the context of the application. An attacker must convince a victim to open a document in order to trigger this vulnerability.
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Analysis
by VulDB Data Team • 05/19/2023
The vulnerability described in CVE-2018-3981 represents a critical heap corruption flaw within the Atlantis Word Processor's document parsing functionality. This issue manifests as an uninitialized pointer vulnerability that occurs during the processing of Microsoft Word documents, specifically within the parser component responsible for handling document structures and content. The flaw is classified under CWE-457 as an use of uninitialized variable, which directly translates to memory safety issues that can be exploited by malicious actors. The vulnerability exists in the context of document processing where the application fails to properly initialize memory pointers before their first use, creating a predictable attack surface for remote code execution.
The technical implementation of this vulnerability involves a specific sequence of operations that begins with an array fetch operation returning an uninitialized pointer value. This uninitialized pointer is then subjected to arithmetic operations before being written to memory, creating a scenario where the pointer contains unpredictable data from previous memory operations. The memory corruption occurs at the heap level, where the uninitialized pointer references memory locations that may contain sensitive data or be in use by other application components. The arithmetic operations performed on this uninitialized pointer can cause it to point to arbitrary memory locations, allowing for controlled memory corruption that can be leveraged to overwrite critical application structures or execute arbitrary code. This type of vulnerability is particularly dangerous because it operates at the memory management level where the application's execution flow can be directly manipulated.
The operational impact of CVE-2018-3981 is severe and can result in complete system compromise when exploited successfully. An attacker requires only social engineering to convince a victim to open a maliciously crafted Word document, making this vulnerability particularly dangerous in enterprise environments where users frequently open documents from external sources. The exploitation process can lead to code execution under the privileges of the Atlantis Word Processor application, potentially allowing attackers to escalate privileges or establish persistent access to affected systems. The heap corruption can also cause application crashes or denial of service conditions, depending on the specific memory locations targeted during the exploitation phase. This vulnerability directly maps to ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage application vulnerabilities to execute malicious code on target systems.
Mitigation strategies for this vulnerability should focus on immediate patching of the Atlantis Word Processor application to address the uninitialized pointer handling in the document parser. Users should implement strict document validation policies and avoid opening documents from untrusted sources, particularly those received via email or downloaded from unknown websites. Network-level protections such as email filtering and web application firewalls can help prevent delivery of malicious documents to users. Additionally, system administrators should consider implementing application whitelisting policies to restrict execution of unauthorized document processing applications. The vulnerability highlights the importance of proper memory initialization practices in software development and demonstrates how seemingly minor issues in memory management can lead to critical security breaches. Organizations should also conduct regular security assessments of their document processing workflows and ensure that all third-party applications undergo proper security testing before deployment.