Windows IIS Components Module Failed to Load

name: Windows IIS Components Module Failed to Load
id: 40c2ba5b-dd6a-496b-9e6e-c9524d0be167
version: 10
creation_date: '2022-12-21'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Anomaly
description: The following analytic detects when an IIS Module DLL fails to load due to a configuration problem, identified by EventCode 2282. This detection leverages Windows Application event logs to identify repeated failures in loading IIS modules. Such failures can indicate misconfigurations or potential tampering with IIS components. If confirmed malicious, this activity could lead to service disruptions or provide an attacker with opportunities to exploit vulnerabilities within the IIS environment. Immediate investigation is required to determine the legitimacy of the failing module and to mitigate any potential security risks.
data_source:
    - Windows Event Log Application 2282
search: |-
    `wineventlog_application` EventCode=2282
      | stats  count min(_time) as firstTime max(_time) as lastTime
        BY EventCode dest Name
           ModuleDll
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_iis_components_module_failed_to_load_filter`
how_to_implement: IIS must be installed and Application event logs must be collected in order to utilize this analytic.
known_false_positives: False positives will be present until all module failures are resolved or reviewed.
references:
    - https://social.technet.microsoft.com/wiki/contents/articles/21757.event-id-2282-iis-worker-process-availability.aspx
    - 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
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: A new IIS Module has been loaded and should be reviewed on $dest$.
analytic_story:
    - IIS Components
asset_type: Endpoint
mitre_attack_id:
    - T1505.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint