Malicious Web Shell Written to a Web Server Root by a Server Worker Process (via file_event)
- Product
- windows
- Category
- file_event
- Author
- HuntRule
- Published
- 2026-07-27
- Updated
- 2026-08-28
ATT&CK techniques
PersistenceRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects a web-server worker process such as the IIS w3wp.exe or a PHP/Java handler writing a server-side script file into a web root, the classic signature of a web shell being planted after exploitation of an internet-facing application. Web shells provide persistent remote access and are a recurring initial-access and persistence technique in the Red Canary Threat Detection Report. Detecting server processes dropping executable web content surfaces the compromise.
Reporting behind it
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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