Malicious SharePoint spinstall0 Webshell Dropped in LAYOUTS Directory (CVE-2025-53770)

ATT&CK techniques

Persistence → Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1505.003Web Shell
Priv Esc
Defense Evasion
Cred Access
- T1552.004Private Keys
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects creation of the spinstall0.aspx webshell within the SharePoint LAYOUTS directory, the payload dropped by ToolShell exploitation to steal machine key material. It is important because this file harvests cryptographic secrets that let attackers forge trusted ViewState payloads for durable access.

Reporting behind it

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Malicious SharePoint spinstall0 Webshell Dropped in LAYOUTS Directory (CVE-2025-53770)

Pivot detection · T1505.003 · 9 related

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