Sigma rule: Suspicious IIS Module Registration

Rule

Title

Suspicious IIS Module Registration

Status

test

Level

high

Author

Florian Roth (Nextron Systems), Microsoft (idea)

Date

2022-08-04

Modified

2023-01-23

File

rules/windows/process_creation/proc_creation_win_iis_susp_module_registration.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects a suspicious IIS module registration as described in Microsoft threat report on IIS backdoors

Log source

product

windows

category

process_creation

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_*

False positives (as the rule lists them)

• Administrative activity

Tags

• attack.persistence
• attack.t1505.004

MITRE ATT&CK ids this rule names

• T1505.004

References

• https://www.microsoft.com/security/blog/2022/07/26/malicious-iis-extensions-quietly-open-persistent-backdoors-into-servers/

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_iis_susp_module_registration.yml