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MediumSplunk security contentMichael Haag +1

Windows SharePoint Spinstall0 Webshell File Creation

This detection identifies the creation or modification of the "spinstall0.aspx" webshell file in Microsoft SharePoint directories. This file is a known indicator of compromise associated with the exploitation of…

Description

This detection identifies the creation or modification of the "spinstall0.aspx" webshell file in Microsoft SharePoint directories. This file is a known indicator of compromise associated with the exploitation of CVE-2025-53770 (ToolShell vulnerability). Attackers exploit the vulnerability to drop webshells that provide persistent access to compromised SharePoint servers, allowing them to execute arbitrary commands, access sensitive data, and move laterally within the network.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.

Log source category
sysmon_eventid_11

Known benign triggers

  • Limited false positives are expected as the spinstall0.aspx file is not a legitimate SharePoint component. However, there might be rare cases where legitimate files with similar names are created during SharePoint updates or maintenance. Verify the process that created the file and the file content to confirm malicious intent.

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