Malicious Web Shell Written to a Web Server Root by a Server Worker Process (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 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

Related detections9 linkedT1505.003 — drag to rearrange

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Malicious Web Shell Written to a Web Server Root by a Server Worker Process (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.

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