Windows IIS Components New Module Added

Description

The following analytic detects the addition of new IIS modules on a Windows IIS server. It leverages the Windows Event log - Microsoft-IIS-Configuration/Operational, specifically EventCode 29, to identify this activity. This behavior is significant because IIS modules are rarely added to production servers, and unauthorized modules could indicate malicious activity. If confirmed malicious, an attacker could use these modules to execute arbitrary code, escalate privileges, or maintain persistence within the environment, potentially compromising the server and sensitive data.

Query · spl

`iis_operational_logs` EventCode=29
  | stats  count min(_time) as firstTime max(_time) as lastTime
    BY OpCode EventCode ComputerName
       Message
  | rename ComputerName AS dest
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `windows_iis_components_new_module_added_filter`

Implementation guide

You must enabled the IIS Configuration Operational log before ingesting in Splunk. Setup and inputs may be found here https://gist.github.com/MHaggis/64396dfd9fc3734e1d1901a8f2f07040.

Known false positives

  • False positives may be present when updates or an administrator adds a new module to IIS. Monitor and filter as needed.

Analyst notes

Known false positives: False positives may be present when updates or an administrator adds a new module to IIS. Monitor and filter as needed.

Raw source Windows IIS Components New Module Added · SPL
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Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Windows IIS Components New Module Added
id: 55f22929-cfd3-4388-ba5c-4d01fac7ee7e
version: 11
creation_date: '2022-12-21'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the addition of new IIS modules on a Windows IIS server. It leverages the Windows Event log - Microsoft-IIS-Configuration/Operational, specifically EventCode 29, to identify this activity. This behavior is significant because IIS modules are rarely added to production servers, and unauthorized modules could indicate malicious activity. If confirmed malicious, an attacker could use these modules to execute arbitrary code, escalate privileges, or maintain persistence within the environment, potentially compromising the server and sensitive data.
data_source:
    - Windows IIS 29
search: |-
    `iis_operational_logs` EventCode=29
      | stats  count min(_time) as firstTime max(_time) as lastTime
        BY OpCode EventCode ComputerName
           Message
      | rename ComputerName AS dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_iis_components_new_module_added_filter`
how_to_implement: You must enabled the IIS Configuration Operational log before ingesting in Splunk. Setup and inputs may be found here https://gist.github.com/MHaggis/64396dfd9fc3734e1d1901a8f2f07040.
known_false_positives: False positives may be present when updates or an administrator adds a new module to IIS. Monitor and filter as needed.
references:
    - https://gist.github.com/MHaggis/64396dfd9fc3734e1d1901a8f2f07040
    - https://www.microsoft.com/en-us/security/blog/2022/12/12/iis-modules-the-evolution-of-web-shells-and-how-to-detect-them/
    - https://www.crowdstrike.com/wp-content/uploads/2022/05/crowdstrike-iceapple-a-novel-internet-information-services-post-exploitation-framework-1.pdf
    - https://unit42.paloaltonetworks.com/unit42-oilrig-uses-rgdoor-iis-backdoor-targets-middle-east/
    - https://www.secureworks.com/research/bronze-union
    - https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1505.004
    - https://strontic.github.io/xcyclopedia/library/appcmd.exe-055B2B09409F980BF9B5A3969D01E5B2.html
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: A new IIS Module has been loaded and should be reviewed on $dest$.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - IIS Components
    - GhostRedirector IIS Module and Rungan Backdoor
asset_type: Endpoint
mitre_attack_id:
    - T1505.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1505.004/IIS-Configuration-Operational.log
          source: IIS:Configuration:Operational
          sourcetype: IIS:Configuration:Operational
      test_type: unit

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