IIS w3wp Suspicious Process Spawn (Turla LunarWeb)

SIGMA detection rule by Dragon-ThreatResearchHQ · Unknown

Detects suspicious child process creation by the IIS worker process w3wp.exe, characteristic of server-side backdoors like Turla LunarWeb executing arbitrary commands.

title: IIS w3wp Suspicious Process Spawn (Turla LunarWeb)
id: c8b02419-7e3f-4221-a5bf-85f7560da423
status: experimental
description: Detects suspicious child process creation by the IIS worker process w3wp.exe, characteristic of server-side backdoors like Turla LunarWeb executing arbitrary commands.
references:
    - https://www.welivesecurity.com/en/eset-research/lunar-toolset-turla-targets-diplomatic-missions/
author: Dragon-ThreatResearchHQ
date: 2024-05-20
modified: 2026-03-01
tags:
    - attack.persistence
    - attack.t1505.004
    - attack.execution
    - attack.t1059.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\w3wp.exe'
    selection_child:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\whoami.exe'
            - '\net.exe'
            - '\net1.exe'
            - '\nltest.exe'
            - '\quser.exe'
    condition: selection_parent and selection_child
falsepositives:
    - Legitimate administration scripts or poorly designed web applications executing administrative tools (should be baselined and excluded).
level: high

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

bb6a8f54-93c8-465f-90c3-22e99ba5eead

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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