CVE-2016-3365 in Office
Summary
by MITRE
Microsoft Excel 2007 SP3, Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel 2016, 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," a different vulnerability than CVE-2016-3362.
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Analysis
by VulDB Data Team • 09/16/2022
The vulnerability identified as CVE-2016-3365 represents a critical memory corruption flaw affecting multiple versions of Microsoft Excel and related Office components. This vulnerability specifically impacts Excel 2007 SP3, Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel 2016, Office Compatibility Pack SP3, Excel Viewer, and various Excel Services implementations on SharePoint Server 2007 SP3, 2010 SP2, and 2013 SP1, as well as Office Online Server. The flaw stems from improper handling of malformed data structures within Excel document parsing routines, creating opportunities for attackers to manipulate memory contents through carefully crafted malicious files. This issue falls under the broader category of memory corruption vulnerabilities that have been classified as CWE-125, representing out-of-bounds read conditions that can lead to arbitrary code execution.
The technical exploitation of this vulnerability occurs when a user opens a specially crafted Excel document that contains malformed data structures designed to trigger memory corruption during the parsing process. Attackers can construct documents that manipulate memory pointers or buffer boundaries in ways that cause the application to execute code from arbitrary memory locations. The vulnerability typically manifests through heap-based memory corruption where attacker-controlled data is processed by Excel's parsing engine, leading to overwrite of critical memory segments or execution of malicious code injected into the application's memory space. This type of exploitation aligns with ATT&CK technique T1059.005, which involves the use of command and scripting interpreter for execution, as the memory corruption can enable attackers to inject and execute malicious code within the Excel process context.
The operational impact of CVE-2016-3365 extends beyond simple code execution, as it represents a significant threat vector for enterprise environments where Excel documents are commonly shared and opened. Organizations utilizing SharePoint Server with Excel Services face particular risk since these components can be accessed remotely and may not require user interaction to process documents, creating potential for automated exploitation. The vulnerability's prevalence across multiple Office versions and server implementations means that organizations with mixed environments face challenges in remediation efforts, as each component requires individual patching and validation. Additionally, the nature of this vulnerability makes it particularly dangerous for targeted attacks, as it can be delivered through email attachments, document sharing platforms, or compromised websites where users may unknowingly open malicious Excel files.
Mitigation strategies for CVE-2016-3365 should focus on both immediate defensive measures and long-term security enhancements. Microsoft released patches addressing this vulnerability through regular security updates, requiring organizations to implement timely patch management procedures across all affected Office versions and SharePoint implementations. Network-based defenses such as email filtering, document validation, and sandboxing techniques can provide additional protection layers by preventing potentially malicious Excel files from reaching end users. Organizations should also implement application whitelisting policies that restrict execution of unauthorized Office components and consider disabling unnecessary Office features that could contribute to exploitation. The vulnerability's classification as a memory corruption issue emphasizes the importance of enabling exploit protection mechanisms such as Data Execution Prevention and Address Space Layout Randomization, which can make exploitation attempts more difficult and less reliable. Regular security assessments and user awareness training regarding suspicious document attachments further complement technical controls in defending against this particular threat vector.