CVE-2016-3358 in Office
Summary
by MITRE
Microsoft Excel 2007 SP3, Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel 2016, Excel 2016 for Mac, Office Compatibility Pack SP3, Excel Viewer, Excel Services on SharePoint Server 2007 SP3, Excel Services on SharePoint Server 2010 SP2, Excel Automation Services on SharePoint Server 2013 SP1, and Office Online Server allow remote attackers to execute arbitrary code via a crafted document, aka "Microsoft Office Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 09/16/2022
This vulnerability represents a critical memory corruption flaw in Microsoft Excel software across multiple versions and platforms. The issue stems from improper handling of specially crafted malicious documents that trigger buffer overflow conditions during document processing. When users open these malformed files, the application's memory management mechanisms fail to properly validate input data, leading to unauthorized code execution in the context of the current user's privileges. The vulnerability affects not only standalone Excel installations but also integrated components such as Excel Services on SharePoint Server and Office Online Server, expanding the potential attack surface significantly.
The technical exploitation of this vulnerability involves crafting specific Office document formats that contain malformed data structures designed to overwrite memory regions beyond allocated buffers. This type of memory corruption typically occurs during parsing operations when Excel attempts to process complex spreadsheet elements such as formulas, charts, or embedded objects. The flaw allows attackers to manipulate memory pointers and execute arbitrary instructions, potentially leading to complete system compromise. According to CWE classification, this vulnerability maps to CWE-125: "Out-of-bounds Read" and CWE-787: "Out-of-bounds Write," both of which fall under the category of memory safety issues that enable privilege escalation and code execution.
The operational impact of CVE-2016-3358 extends beyond individual user systems to enterprise environments where Excel is widely deployed for business operations. Attackers can leverage this vulnerability through social engineering campaigns targeting office workers with malicious Excel documents delivered via email attachments or compromised websites. The vulnerability's presence in SharePoint Server components means that organizations with web-based Excel processing capabilities face additional exposure. Successful exploitation can result in data theft, system takeover, and lateral movement within networks, making it particularly dangerous for enterprise environments. The ATT&CK framework categorizes this as a technique involving "Exploitation for Client Execution" under the T1203 category, which specifically addresses vulnerabilities in office applications.
Mitigation strategies for this vulnerability require immediate patch deployment from Microsoft, as the company released security updates addressing the memory corruption issues in affected versions. Organizations should implement strict email filtering and document validation policies to prevent malicious files from reaching end users. Network segmentation and privilege separation can help limit the potential damage if exploitation occurs. Security teams should also consider implementing application whitelisting policies that restrict execution of untrusted Office documents, particularly those opened from external sources. Regular security awareness training for employees remains crucial in preventing successful social engineering attacks that leverage this vulnerability. Additionally, monitoring for suspicious Office document processing activities and implementing endpoint detection solutions can help identify exploitation attempts before they succeed.