Potential DLL File Download Via PowerShell Invoke-WebRequest

Hunt Hypothesis

Detects potential DLL files being downloaded using the PowerShell Invoke-WebRequest or Invoke-RestMethod cmdlets.

Detection Rule

Sigma (Original)

title: Potential DLL File Download Via PowerShell Invoke-WebRequest
id: 0f0450f3-8b47-441e-a31b-15a91dc243e2
status: test
description: Detects potential DLL files being downloaded using the PowerShell Invoke-WebRequest or Invoke-RestMethod cmdlets.
references:
    - https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
author: Florian Roth (Nextron Systems), Hieu Tran
date: 2023-03-13
modified: 2025-07-18
tags:
    - attack.command-and-control
    - attack.execution
    - attack.t1059.001
    - attack.t1105
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        CommandLine|contains:
            - 'Invoke-RestMethod '
            - 'Invoke-WebRequest '
            - 'IRM '
            - 'IWR '
        CommandLine|contains|all:
            - 'http'
            - 'OutFile'
            - '.dll'
    condition: selection
falsepositives:
    - Unknown
level: medium

KQL (Azure Sentinel)

imProcessCreate
| where (TargetProcessCommandLine contains "Invoke-RestMethod " or TargetProcessCommandLine contains "Invoke-WebRequest " or TargetProcessCommandLine contains "IRM " or TargetProcessCommandLine contains "IWR ") and (TargetProcessCommandLine contains "http" and TargetProcessCommandLine contains "OutFile" and TargetProcessCommandLine contains ".dll")

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Command and Control
• Tactic: Execution
• Technique: T1059.001 — PowerShell
• Technique: T1105 — T1105

References

• https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
• SigmaHQ Rule