CVE-2018-0841 in Excel
Summary
by MITRE
Microsoft Office 2016 Click-to-Run allows a remote code execution vulnerability due to how objects are handled in memory, aka "Office Remote Code Execution Vulnerability"
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Analysis
by VulDB Data Team • 02/03/2021
The CVE-2018-0841 vulnerability represents a critical remote code execution flaw in Microsoft Office 2016 Click-to-Run implementation that stems from improper handling of objects within memory structures. This vulnerability specifically affects the way Office applications process certain file objects, creating opportunities for attackers to execute arbitrary code on affected systems. The flaw exists in the memory management mechanisms that govern how Office applications handle various object types during document processing, particularly when dealing with malformed or specially crafted input files. Security researchers identified that the vulnerability manifests when Office applications attempt to parse and render objects within Office documents, leading to memory corruption that can be exploited by malicious actors.
The technical root cause of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where programs access memory locations beyond the intended boundaries. In the context of CVE-2018-0841, the flaw occurs during the object handling process where Office applications fail to properly validate the size and structure of memory objects before processing them. This improper validation creates a scenario where attacker-controlled data can overwrite adjacent memory locations, potentially leading to arbitrary code execution. The vulnerability is particularly dangerous because it can be triggered through social engineering attacks where users open malicious Office documents, making it a prime target for phishing campaigns and targeted attacks.
From an operational impact perspective, this vulnerability presents significant risks to enterprise environments where Microsoft Office is widely deployed. The remote code execution capability means that attackers can potentially gain full system control without requiring local access, making it particularly dangerous for organizations with limited network segmentation. The vulnerability affects multiple Office applications including Word, Excel, and PowerPoint, which are commonly used across enterprise networks, amplifying the potential attack surface. Organizations that rely heavily on Office documents for business operations face heightened risk of data breaches, system compromise, and potential lateral movement within their networks. The vulnerability's exploitability through email attachments makes it particularly attractive to threat actors conducting large-scale campaigns.
The mitigation strategies for CVE-2018-0841 primarily involve applying Microsoft's security updates and patches as soon as they become available. Organizations should implement immediate patch management procedures to address this vulnerability across all affected Office installations. Additionally, network administrators should consider implementing email filtering solutions that can detect and block malicious Office documents before they reach end users. Security teams should also deploy application whitelisting policies to restrict execution of Office applications from untrusted sources and implement strict file validation mechanisms. According to ATT&CK framework, this vulnerability maps to T1203 - Exploitation for Client Execution and T1059 - Command and Scripting Interpreter, highlighting the need for comprehensive endpoint protection measures. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior patterns associated with exploitation attempts, particularly focusing on unusual network connections or file access patterns that may indicate successful exploitation of this vulnerability.