Detection rules › Sigma
Suspicious IIS Module Registration
Detects a suspicious IIS module registration as described in Microsoft threat report on IIS backdoors
Known false positives
- Administrative activity
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence |
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Sysmon | Event ID 1: Process creation |
| Security-Auditing | Event ID 4688: A new process has been created. |
Rule body
title: Suspicious IIS Module Registration
id: 043c4b8b-3a54-4780-9682-081cb6b8185c
status: test
description: Detects a suspicious IIS module registration as described in Microsoft threat report on IIS backdoors
references:
- https://www.microsoft.com/security/blog/2022/07/26/malicious-iis-extensions-quietly-open-persistent-backdoors-into-servers/
author: Florian Roth (Nextron Systems), Microsoft (idea)
date: 2022-08-04
modified: 2023-01-23
tags:
- attack.persistence
- attack.t1505.004
logsource:
category: process_creation
product: windows
detection:
selection_parent:
ParentImage|endswith: '\w3wp.exe'
selection_cli_1:
CommandLine|contains: 'appcmd.exe add module'
selection_cli_2:
CommandLine|contains: ' system.enterpriseservices.internal.publish'
Image|endswith: '\powershell.exe'
selection_cli_3:
CommandLine|contains|all:
- 'gacutil'
- ' /I'
condition: selection_parent and 1 of selection_cli_*
falsepositives:
- Administrative activity
level: high
Stages and Predicates
Stage 0: condition
selection_parent and 1 of selection_cli_*Stage 1: selection_parent
selection_parent:
ParentImage|endswith: '\w3wp.exe'
Stage 2: selection_cli_1
selection_cli_1:
CommandLine|contains: 'appcmd.exe add module'
Stage 3: selection_cli_2
selection_cli_2:
CommandLine|contains: ' system.enterpriseservices.internal.publish'
Image|endswith: '\powershell.exe'
Stage 4: selection_cli_3
selection_cli_3:
CommandLine|contains|all:
- 'gacutil'
- ' /I'
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
CommandLine | match |
| field:"CommandLine" kind:match |
Image | ends_with |
| field:"Image" kind:ends_with value:"\powershell.exe" |
ParentImage | ends_with |
| field:"ParentImage" kind:ends_with value:"\w3wp.exe" |