CVE-2018-8502 in Office
Summary
by MITRE
A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle objects in Protected View, aka "Microsoft Excel Remote Code Execution Vulnerability." This affects Office 365 ProPlus, Microsoft Office, Microsoft Excel.
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Analysis
by VulDB Data Team • 05/23/2023
This vulnerability represents a critical remote code execution flaw in Microsoft Excel software that arises from improper handling of objects within Protected View mode. The issue stems from how Excel processes certain file objects when they are opened in Protected View, which is designed to prevent potentially malicious content from executing automatically. When Excel encounters specific malformed or crafted objects within these protected files, the software fails to properly validate or sanitize the input, creating an execution path that adversaries can exploit to run arbitrary code on affected systems. The vulnerability specifically impacts Microsoft Office 365 ProPlus, Microsoft Office installations, and Microsoft Excel across various versions, making it a widespread concern for enterprise environments that rely heavily on these productivity applications.
The technical nature of this flaw falls under CWE-119, which describes weaknesses related to insufficient control of a resource's size, and specifically relates to improper handling of objects in memory. Attackers can craft malicious Excel files that contain specially formatted objects designed to trigger buffer overflows or memory corruption when processed by Excel's Protected View mechanism. This vulnerability operates at the application layer and requires user interaction to exploit, as the malicious file must first be opened for the code execution to occur. The attack vector typically involves social engineering campaigns where users are tricked into opening seemingly legitimate Excel documents that contain the malicious payload. The exploitation process leverages the fact that Protected View, which is intended to provide security by preventing automatic execution of potentially harmful content, actually contains a flaw that allows malicious code to bypass these protections when processing specific object types.
The operational impact of this vulnerability extends beyond individual system compromise to threaten entire enterprise networks and organizational security postures. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the logged-in user, potentially leading to full system compromise, data exfiltration, and lateral movement within network environments. Organizations using Microsoft Office products are particularly vulnerable since these applications are widely deployed across business environments, making the attack surface extensive. The vulnerability's designation as a remote code execution flaw means that attackers can potentially exploit it from external networks without requiring physical access to target systems, making it especially dangerous for organizations with limited network segmentation or robust endpoint protection measures. This type of vulnerability directly impacts the confidentiality, integrity, and availability of organizational data and systems, potentially leading to significant financial losses, regulatory compliance violations, and reputational damage.
Mitigation strategies for this vulnerability should focus on multiple defensive layers to protect against exploitation attempts. Microsoft released security patches and updates that address the specific handling of objects within Protected View, requiring immediate deployment across all affected systems. Organizations should implement strict email filtering and content inspection mechanisms to prevent malicious Excel files from reaching end users, particularly focusing on identifying and blocking files with suspicious object structures. Network segmentation and privileged access controls can limit the potential impact if exploitation occurs, while endpoint detection and response solutions can help identify anomalous behavior associated with exploitation attempts. Security awareness training programs should educate users about recognizing potentially malicious Office documents and the risks of opening unexpected files, as user interaction remains a required component for exploitation. Additionally, implementing application whitelisting policies that restrict execution of unauthorized Office applications can provide an additional barrier against exploitation attempts, while regular security assessments and vulnerability scanning should be conducted to identify any remaining exposure risks within the organization's attack surface.