huntrule

Windows File Creation in SharePoint Web Server Extensions Suggesting ToolShell Drop

Alerts on Windows file creations within SharePoint Web Server Extensions that match suspicious spinstall/debug artifacts linked to CVE-2025-53770.

FreeReviewedSigma · Critical · v5
Product
windows
Category
file_event
Author
Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2025-07-21
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags creation of files within SharePoint Web Server Extensions paths, with filename patterns consistent with ToolShell-style payload drops (for example spinstall*.aspx and debug_dev.js under template layouts). Attackers may create these web-accessible files to gain execution or persist during exploitation attempts. Telemetry required is Windows file event data that includes the full TargetFilename for newly created or written files.

Reporting behind it

Related detections9 linkedT1190 — drag to rearrange
Malicious SharePoint ToolShell Post-Exploitation via Encoded PowerShell (via process_creation)
Malicious Web Shell Written to SharePoint LAYOUTS Directory by Worker Process (via file_event)
Malicious MS-SQL Server Spawning Command Shell via Mallox
Malicious ActiveMQ CVE-2023-46604 Payload Download via curl or wget
Malicious WordPress Core SQL Injection Scanner via User-Agent
Malicious Command Shell Spawned by SQL Server via Process Creation (via process_creation)
Malicious Command Shell or PowerShell Spawned by Tomcat via Process Creation (via process_creation)
Suspicious Shell Script Execution From Temp Directory on SonicWall SMA1000 Appliance (via process_creation)
Possible TP-Link Command Injection via WlanNetworkRpm Endpoint (via webserver)
Windows File Creation in SharePoint Web Server Extensions Suggesting ToolShell Drop
Pivot detection · T1190 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.