Remote File Download Via Desktopimgdownldr Utility

Hunt Hypothesis

Detects the desktopimgdownldr utility being used to download a remote file. An adversary may use desktopimgdownldr to download arbitrary files as an alternative to certutil.

Detection Rule

Sigma (Original)

title: Remote File Download Via Desktopimgdownldr Utility
id: 214641c2-c579-4ecb-8427-0cf19df6842e
status: test
description: Detects the desktopimgdownldr utility being used to download a remote file. An adversary may use desktopimgdownldr to download arbitrary files as an alternative to certutil.
references:
    - https://www.elastic.co/guide/en/security/current/remote-file-download-via-desktopimgdownldr-utility.html
author: Tim Rauch, Elastic (idea)
date: 2022-09-27
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\desktopimgdownldr.exe'
        ParentImage|endswith: '\desktopimgdownldr.exe'
        CommandLine|contains: '/lockscreenurl:http'
    condition: selection
falsepositives:
    - Unknown
level: medium

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessName endswith "\\desktopimgdownldr.exe" and (ParentProcessName endswith "\\desktopimgdownldr.exe" or ActingProcessName endswith "\\desktopimgdownldr.exe") and TargetProcessCommandLine contains "/lockscreenurl:http"

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Command and Control
• Technique: T1105 — T1105

References

• https://www.elastic.co/guide/en/security/current/remote-file-download-via-desktopimgdownldr-utility.html
• SigmaHQ Rule