CVE-2023-33137 in Excel
Summary
by MITRE • 06/14/2023
Microsoft Excel Remote Code Execution Vulnerability
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/07/2024
This vulnerability represents a critical remote code execution flaw in Microsoft Excel software that allows attackers to execute arbitrary code on affected systems without user interaction. The vulnerability stems from improper handling of specially crafted Excel files that contain malicious content, particularly when these files are opened or processed by the application. Security researchers have identified that the flaw exists within Excel's parsing mechanisms for specific file formats and data structures, creating opportunities for exploitation through various attack vectors including email attachments, web downloads, or malicious documents shared via collaboration platforms.
The technical implementation of this vulnerability involves memory corruption issues that occur when Excel attempts to process malformed or specially crafted spreadsheet elements. Attackers can manipulate the application's handling of certain data types such as formulas, graphics, or embedded objects to trigger buffer overflows, heap corruption, or other memory management errors. These conditions enable malicious code injection directly into the Excel process memory space, bypassing standard security controls and potentially allowing full system compromise. The vulnerability is particularly dangerous because it can be triggered through automated processes or when users open seemingly legitimate documents, making traditional user awareness-based defenses ineffective.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and potential lateral movement within network environments. Successful exploitation can result in unauthorized access to sensitive data, persistence mechanisms installation, privilege escalation to SYSTEM level privileges, and establishment of command and control channels. Organizations using Microsoft Excel in their daily operations face significant risk exposure since the vulnerability can be exploited through multiple attack surfaces including email systems, file sharing platforms, and web applications that process Excel files. The widespread adoption of Excel across enterprise environments means that a single compromised system can serve as a foothold for broader network infiltration.
Mitigation strategies should focus on immediate patch management implementation alongside layered defensive measures to reduce exploitation risk. Microsoft has released security updates addressing this vulnerability through regular monthly patches, and organizations must prioritize timely deployment of these fixes. Additional protective measures include implementing strict file type filtering at network perimeters, disabling automatic execution of macros in Excel, configuring application whitelisting policies, and monitoring for suspicious file access patterns. Security professionals should also consider deploying email filtering solutions that can identify and quarantine potentially malicious Office documents before they reach end users. The vulnerability aligns with several CWE categories including CWE-121 for heap-based buffer overflow and CWE-125 for out-of-bounds read conditions, while also mapping to ATT&CK techniques such as T1059 for command and scripting interpreter usage and T1078 for valid accounts exploitation. Organizations should conduct comprehensive vulnerability assessments to identify systems running affected Excel versions and implement network segmentation to limit the potential impact of successful exploitation attempts.