CVE-2018-8375 in Excel
Summary
by MITRE
A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle objects in memory, aka "Microsoft Excel Remote Code Execution Vulnerability." This affects Microsoft Excel Viewer, Microsoft Office, Microsoft Excel. This CVE ID is unique from CVE-2018-8379.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2018-8375 represents a critical remote code execution flaw within Microsoft Excel software that stems from improper handling of objects in memory. This vulnerability affects multiple Microsoft Office products including Excel Viewer, full Office suite installations, and Excel specifically, making it a widespread concern across enterprise and individual computing environments. The flaw manifests when Excel processes certain file formats or objects that trigger memory corruption conditions, potentially allowing attackers to execute arbitrary code on affected systems. This vulnerability is particularly concerning because it operates at the memory management level, where improper object handling can lead to complete system compromise without requiring user interaction beyond opening a malicious file. The vulnerability is classified under CWE-125 as "Out-of-bounds Read" and aligns with ATT&CK technique T1059.005 for "Command and Scripting Interpreter: Visual Basic", as attackers can leverage this flaw to execute malicious code through Office macros or similar mechanisms.
The technical exploitation of CVE-2018-8375 occurs when Excel encounters specially crafted objects within spreadsheet files that cause memory corruption during normal processing operations. This typically involves malformed data structures or objects that exceed expected memory boundaries, leading to memory overwrite conditions or pointer corruption. Attackers can construct malicious Excel files that trigger these memory handling failures when opened, potentially leading to arbitrary code execution with the privileges of the user running Excel. The vulnerability's remote execution capability means attackers can deliver malicious files through email attachments, web downloads, or other remote delivery mechanisms without requiring physical access to target systems. The flaw demonstrates poor memory management practices in Excel's object handling routines, where insufficient bounds checking or improper memory allocation leads to exploitable conditions. This vulnerability is particularly dangerous in enterprise environments where users frequently open files from untrusted sources, making it a prime target for phishing campaigns and targeted attacks.
The operational impact of CVE-2018-8375 extends far beyond simple data corruption, as successful exploitation can result in complete system compromise and persistent access for attackers. Organizations running affected versions of Microsoft Excel are vulnerable to sophisticated attacks that can lead to data breaches, lateral movement within networks, and establishment of backdoors for continued access. The vulnerability's presence in Excel Viewer makes it particularly dangerous as this component is often installed on systems where users may not have administrative privileges, yet still represent potential entry points for attackers. The exploitability of this vulnerability is enhanced by the fact that Excel's memory handling flaws can be triggered automatically when files are opened, requiring no user interaction beyond the initial file opening. This characteristic makes it particularly effective in phishing attacks where a single malicious attachment can compromise multiple systems, especially in environments where users regularly open spreadsheet files from external sources. The vulnerability's classification as a remote code execution flaw means that attackers can potentially establish command and control channels, exfiltrate sensitive data, or deploy additional malware payloads.
Mitigation strategies for CVE-2018-8375 should prioritize immediate patch deployment from Microsoft as the primary defense mechanism. Organizations should ensure all users have the latest security updates installed, particularly the cumulative updates released by Microsoft to address this specific vulnerability. Network segmentation and email filtering should be implemented to reduce the attack surface, preventing users from opening potentially malicious files. Security awareness training programs should emphasize the dangers of opening unexpected spreadsheet files, particularly those received via email. System administrators should consider implementing application whitelisting policies that restrict execution of unauthorized Office macros or external processes. Regular security audits should verify that all Office installations are properly patched and that users have appropriate access controls. The vulnerability's memory corruption nature makes it particularly susceptible to exploit mitigation techniques such as address space layout randomization and data execution prevention. Organizations should also implement monitoring solutions that can detect anomalous Excel processes or memory access patterns that may indicate exploitation attempts. Given the vulnerability's classification as a remote code execution flaw, continuous network monitoring and endpoint detection capabilities are essential for early identification of potential attacks. The mitigation approach should align with Microsoft's recommended security practices and industry standards for protecting against memory corruption vulnerabilities.