Corelight - Possible Webshell

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Id	f3245aa1-1ca1-471c-a0b7-97ea6b791d5d
Rulename	Corelight - Possible Webshell
Description	Detects post requests to unusual extensions.
Severity	Medium
Tactics	Persistence
Techniques	T1505
Required data connectors	Corelight
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightPossibleWebshell.yaml
Version	2.1.0
Arm template	f3245aa1-1ca1-471c-a0b7-97ea6b791d5d.json

KQL

corelight_http
| where method in~ ('POST', 'PUT')
| where toint(status_code) between (200 .. 299)
| where request_body_len != 0 or response_body_len != 0
| extend fe = extract(@'.*(\.\w+)$', 1, uri)
| where fe in~ ('.jpg', '.jpeg', '.gif', '.png', '.icon', '.ico', '.xml', '.swf', '.svg', '.ppt', '.pttx', '.doc', '.docx', '.rtf', '.pdf', '.tif', '.zip', '.mov')

YAML

queryPeriod: 1h
description: |
    'Detects post requests to unusual extensions.'
kind: Scheduled
query: |
  corelight_http
  | where method in~ ('POST', 'PUT')
  | where toint(status_code) between (200 .. 299)
  | where request_body_len != 0 or response_body_len != 0
  | extend fe = extract(@'.*(\.\w+)$', 1, uri)
  | where fe in~ ('.jpg', '.jpeg', '.gif', '.png', '.icon', '.ico', '.xml', '.swf', '.svg', '.ppt', '.pttx', '.doc', '.docx', '.rtf', '.pdf', '.tif', '.zip', '.mov')  
tactics:
- Persistence
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightPossibleWebshell.yaml
id: f3245aa1-1ca1-471c-a0b7-97ea6b791d5d
version: 2.1.0
entityMappings:
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: id_orig_h
triggerThreshold: 0
status: Available
relevantTechniques:
- T1505
name: Corelight - Possible Webshell
severity: Medium
requiredDataConnectors:
- dataTypes:
  - Corelight_v2_http
  - corelight_http
  connectorId: Corelight
queryFrequency: 1h

ARM