^{CVE-2020-1147:}Remote Code Execution Vulnerability in .NET Framework, SharePoint, and Visual Studio

Overview

This vulnerability stems from an insecure deserialization issue in the DataSet and DataTable components within .NET Framework. When processing XML input, the affected applications do not properly validate the source markup, which allows attackers to inject malicious code that gets executed during the deserialization process. In SharePoint environments, this can be exploited through document uploads or other file processing features.

The vulnerability affects multiple Microsoft products:

• .NET Framework
• SharePoint Server (multiple versions)
• Visual Studio

Successful exploitation could allow attackers to run arbitrary code with the privileges of the application processing the malicious XML content. In web-based scenarios like SharePoint, this could lead to complete compromise of the affected server.

Remediation

To mitigate this vulnerability, the following actions are recommended:

1. Apply the appropriate security updates from Microsoft:

   • Install the July 2020 security updates for all affected products
   • Ensure .NET Framework installations are updated to the latest patched versions
   • Update SharePoint Server installations with the latest security patches

2. Implement additional security measures:

   • Restrict access to SharePoint document libraries and file upload functionality
   • Implement proper input validation for all file uploads
   • Consider implementing network segmentation to limit exposure of SharePoint servers
   • Review and restrict user permissions to minimize the impact of potential exploitation

3. Monitor systems for suspicious activity:

   • Watch for unexpected process executions
   • Monitor for unusual file uploads or document processing activities
   • Enable enhanced logging on SharePoint servers

References

1. Microsoft Security Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1147

2. Exploit Information:

   • SharePoint DataSet/DataTable Deserialization: http://packetstormsecurity.com/files/158694/SharePoint-DataSet-DataTable-Deserialization.html
   • Microsoft SharePoint Server 2019 Remote Code Execution: http://packetstormsecurity.com/files/158876/Microsoft-SharePoint-Server-2019-Remote-Code-Execution.html
   • Additional SharePoint Server 2019 RCE exploit: http://packetstormsecurity.com/files/163644/Microsoft-SharePoint-Server-2019-Remote-Code-Execution.html

3. Additional Resources:

   • Exploit Alert: https://www.exploitalert.com/view-details.html?id=35992