CVE-2017-8632 in Excel
Summary
by MITRE
A remote code execution vulnerability exists in Microsoft Excel 2010 Service Pack 2, Microsoft Excel 2013 Service Pack 1, Microsoft Excel 2013 RT Service Pack 1, Microsoft Excel 2016, Microsoft Office Web Apps 2013, Microsoft Excel for Mac 2011, Microsoft Excel 2016 for Mac, and Microsoft Office Compatibility Pack Service Pack 3, when they fail to properly handle objects in memory, aka "Microsoft Office Memory Corruption Vulnerability". This CVE ID is unique from CVE-2017-8630, CVE-2017-8631, and CVE-2017-8744.
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Analysis
by VulDB Data Team • 01/11/2021
The vulnerability described in CVE-2017-8632 represents a critical memory corruption flaw affecting multiple versions of Microsoft Excel and Office applications, classified under CWE-125 as an out-of-bounds read condition. This vulnerability manifests when affected applications fail to properly validate and handle objects in memory during processing of maliciously crafted Excel files. The flaw specifically impacts Microsoft Excel 2010 Service Pack 2, Excel 2013 Service Pack 1, Excel 2013 RT Service Pack 1, Excel 2016, Office Web Apps 2013, Excel for Mac 2011, Excel 2016 for Mac, and the Office Compatibility Pack Service Pack 3, creating a widespread attack surface across Microsoft's Office ecosystem. The vulnerability is particularly concerning as it enables remote code execution, allowing attackers to execute arbitrary code on vulnerable systems without requiring local access or user interaction beyond opening a malicious file.
The technical exploitation of this vulnerability occurs through memory corruption techniques that leverage improper handling of structured data within Excel's memory management systems. When a user opens a specially crafted Excel file containing malicious data structures, the application's memory handling routines fail to properly validate object boundaries, leading to memory corruption that can be leveraged by attackers to inject and execute malicious code. This type of vulnerability aligns with ATT&CK technique T1059.005 for command and scripting interpreter and T1203 for exploitation for client execution, as it enables attackers to execute code remotely through compromised Office applications. The memory corruption aspect specifically relates to CWE-121, heap-based buffer overflow, where the application's heap management fails to properly handle memory allocation and deallocation of Excel object structures.
The operational impact of CVE-2017-8632 extends beyond simple remote code execution to encompass significant security implications for enterprise environments. Organizations using affected Microsoft Office versions face potential compromise of their entire network infrastructure, as successful exploitation can lead to full system control and data exfiltration capabilities. The vulnerability's remote nature means that attackers can exploit it through various attack vectors including email attachments, web downloads, or compromised websites, making it particularly dangerous for organizations with limited endpoint protection. The fact that this vulnerability affects multiple Office versions and platforms increases the attack surface significantly, as it requires administrators to patch numerous applications across different operating systems and deployment scenarios. Organizations may experience business disruption, regulatory compliance issues, and potential data breaches, with the vulnerability's exploitation potentially leading to persistent backdoors and lateral movement within networks.
Mitigation strategies for CVE-2017-8632 should include immediate deployment of Microsoft security updates and patches released through the Microsoft Security Response Center. Organizations should implement restrictive file handling policies, including disabling automatic execution of macros and implementing strict file validation for Excel files received from external sources. Network-based mitigations such as email filtering, web proxy configuration, and application control policies can help reduce exposure by blocking malicious file types and preventing users from accessing potentially compromised content. Additionally, implementing security awareness training to educate users about phishing threats and suspicious email attachments can significantly reduce successful exploitation attempts. The vulnerability's classification as a memory corruption issue also necessitates enhanced monitoring for unusual memory access patterns and process behavior, with security teams implementing endpoint detection and response solutions that can identify potential exploitation attempts. Organizations should also consider implementing principle of least privilege access controls and regular security assessments to ensure comprehensive protection against this and similar vulnerabilities.