Malicious ASPX Web Shell Written to SharePoint LAYOUTS Directory (via file_event)

ATT&CK techniques

Persistence

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

What it detects

This rule detects creation of ASPX files within the SharePoint TEMPLATE LAYOUTS directory, where ToolShell exploitation drops an environmentally unique web shell. Writing executable ASPX content into this server-side path establishes a persistent backdoor for continued access after CVE-2025-53770 exploitation.

Reporting behind it

Related detections9 linkedT1505.003 — drag to rearrange

Suspicious PHP Webshell in Netscaler VPN Theme Directory

Suspicious IIS Worker Process Spawning Whoami Reconnaissance

Malicious Web Server Spawning Command Shell and curl Download via Webshell

Malicious IIS Worker Process Spawning PowerShell via Gladinet CentreStack Exploit

Exchange Worker Process Spawning Command Shell via OWASSRF

Suspicious PowerShell Spawned by SysAid Java Process

Suspicious PHP File Written to FreePBX Custom Firmware Directory (via file_event)

Possible Ivanti EPMM In-Memory Java Webshell Access via mifs 403.jsp

Malicious Command Execution Spawned by SharePoint w3wp Worker Process

Malicious ASPX Web Shell Written to SharePoint LAYOUTS Directory (via file_event)

Pivot detection · T1505.003 · 9 related

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

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →