IIS WebServer Log Deletion via CommandLine Utilities — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: medium. Source dates: 2025-09-02 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 839a2eb81042980ab9e3eb040b1146af23686e9c322f3388f906695943dcdbc3

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: IIS WebServer Log Deletion via CommandLine Utilities
id: 0649be4a-aeb0-45b0-b89e-7f1668f6d9c0
related:
    - id: 3eb8c339-a765-48cc-a150-4364c04652bf
      type: similar
status: experimental
description: |
    Detects attempts to delete Internet Information Services (IIS) log files via command line utilities, which is a common defense evasion technique used by attackers to cover their tracks.
    Threat actors often abuse vulnerabilities in web applications hosted on IIS servers to gain initial access and later delete IIS logs to evade detection.
references:
    - https://learn.microsoft.com/en-us/iis/manage/provisioning-and-managing-iis/managing-iis-log-file-storage
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-09-02
tags:
    - attack.stealth
    - attack.t1070
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\cmd.exe'
              - '\powershell_ise.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'cmd.exe'
              - 'powershell.exe'
              - 'powershell_ise.exe'
              - 'pwsh.dll'
    selection_cli_del:
        CommandLine|contains:
            - 'del '
            - 'erase '
            - 'rm '
            - 'remove-item '
            - 'rmdir '
    selection_cli_iis_dir:
        CommandLine|contains: '\inetpub\logs\'
    condition: all of selection_*
falsepositives:
    - Deletion of IIS logs that are older than a certain retention period as part of regular maintenance activities.
    - Legitimate schedule tasks or scripts that clean up log files regularly.
    # More Fp cases
    # https://learn.microsoft.com/en-us/iis/manage/provisioning-and-managing-iis/managing-iis-log-file-storage#02
level: medium

Original YAML and metadata in JSON

False positives

• Deletion of IIS logs that are older than a certain retention period as part of regular maintenance activities.
• Legitimate schedule tasks or scripts that clean up log files regularly.

Source references

• https://learn.microsoft.com/en-us/iis/manage/provisioning-and-managing-iis/managing-iis-log-file-storage