Suspicious Desktopimgdownldr Command — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2020-07-03 / 2021-11-27.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e8856d32ad41a4c065ab0be1a4e430987d793d02f1d2c70ce42a70007b7b2cfd

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: Suspicious Desktopimgdownldr Command
id: bb58aa4a-b80b-415a-a2c0-2f65a4c81009
status: test
description: Detects a suspicious Microsoft desktopimgdownldr execution with parameters used to download files from the Internet
references:
    - https://labs.sentinelone.com/living-off-windows-land-a-new-native-file-downldr/
    - https://twitter.com/SBousseaden/status/1278977301745741825
author: Florian Roth (Nextron Systems)
date: 2020-07-03
modified: 2021-11-27
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection1:
        CommandLine|contains: ' /lockscreenurl:'
    selection1_filter:
        CommandLine|contains:
            - '.jpg'
            - '.jpeg'
            - '.png'
    selection_reg:
        CommandLine|contains|all:
            - 'reg delete'
            - '\PersonalizationCSP'
    condition: ( selection1 and not selection1_filter ) or selection_reg
falsepositives:
    - False positives depend on scripts and administrative tools used in the monitored environment
level: high

Original YAML and metadata in JSON

False positives

• False positives depend on scripts and administrative tools used in the monitored environment

Source references

• https://labs.sentinelone.com/living-off-windows-land-a-new-native-file-downldr/
• https://twitter.com/SBousseaden/status/1278977301745741825