CVE-2016-3233 in Office
Summary
by MITRE
Microsoft Excel 2007 SP3, Excel 2010 SP2, and Office Compatibility Pack SP3 allow remote attackers to execute arbitrary code via a crafted Office document, aka "Microsoft Office Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 08/23/2022
This vulnerability represents a critical memory corruption flaw in Microsoft Excel applications that affects versions 2007 SP3, 2010 SP2, and the Office Compatibility Pack SP3. The vulnerability stems from improper handling of malformed Office document structures during the parsing process, creating opportunities for attackers to manipulate memory contents through carefully crafted malicious files. The flaw specifically manifests when Excel attempts to process certain elements within Office documents, leading to unpredictable memory behavior that can be exploited to achieve arbitrary code execution.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where applications access memory locations beyond allocated buffers. Attackers can exploit this by creating specially constructed Office documents containing malformed data structures that cause Excel to read beyond intended memory boundaries. This memory corruption can be leveraged to overwrite critical memory locations, potentially allowing attackers to inject and execute malicious code with the privileges of the targeted user. The vulnerability is particularly dangerous because it can be triggered through standard document opening mechanisms, requiring no special user interaction beyond opening the malicious file.
The operational impact of CVE-2016-3233 extends beyond simple code execution to encompass significant security risks in enterprise environments where Excel is commonly used for document processing. Organizations with default Excel configurations are particularly vulnerable as attackers can deliver malicious documents through email attachments, web downloads, or malicious websites without requiring any user interaction beyond opening the file. This makes the vulnerability particularly attractive to threat actors conducting phishing campaigns or targeted attacks. The exploitation typically results in complete system compromise when successful, as attackers can leverage the arbitrary code execution to install backdoors, steal data, or establish persistent access to compromised systems.
Mitigation strategies for this vulnerability should encompass multiple layers of defense including immediate patch deployment for all affected Microsoft Office versions, implementation of email filtering and web content protection measures, and user education regarding suspicious document attachments. Security professionals should also consider implementing application whitelisting policies to restrict execution of unauthorized Office document handlers and monitor for unusual file access patterns. The vulnerability demonstrates the importance of keeping Office applications updated and following Microsoft's security advisory practices, as this flaw represents a classic example of how memory corruption vulnerabilities can be exploited in real-world scenarios. Organizations should also implement network segmentation and access controls to limit the potential damage from successful exploitation attempts.