sigmahighHunting

Suspicious PowerShell Download and Execute Pattern

Detects suspicious PowerShell download patterns that are often used in malicious scripts, stagers or downloaders (make sure that your backend applies the strings case-insensitive)

MITRE ATT&CK

T1059.001

execution

Detection Query

selection:
  CommandLine|contains:
    - IEX ((New-Object Net.WebClient).DownloadString
    - IEX (New-Object Net.WebClient).DownloadString
    - IEX((New-Object Net.WebClient).DownloadString
    - IEX(New-Object Net.WebClient).DownloadString
    - " -command (New-Object System.Net.WebClient).DownloadFile("
    - " -c (New-Object System.Net.WebClient).DownloadFile("
condition: selection

Author

Florian Roth (Nextron Systems)

Created

2022-02-28

Data Sources

windowsProcess Creation Events

Platforms

windows

References

Tags

attack.executionattack.t1059.001

Raw Content

title: Suspicious PowerShell Download and Execute Pattern
id: e6c54d94-498c-4562-a37c-b469d8e9a275
related:
    - id: 3b6ab547-8ec2-4991-b9d2-2b06702a48d7
      type: derived
status: test
description: Detects suspicious PowerShell download patterns that are often used in malicious scripts, stagers or downloaders (make sure that your backend applies the strings case-insensitive)
references:
    - https://gist.github.com/jivoi/c354eaaf3019352ce32522f916c03d70
    - https://www.trendmicro.com/en_us/research/22/j/lv-ransomware-exploits-proxyshell-in-attack.html
author: Florian Roth (Nextron Systems)
date: 2022-02-28
modified: 2022-03-01
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: # make sure that your backend applies the strings case-insensitive
            - 'IEX ((New-Object Net.WebClient).DownloadString'
            - 'IEX (New-Object Net.WebClient).DownloadString'
            - 'IEX((New-Object Net.WebClient).DownloadString'
            - 'IEX(New-Object Net.WebClient).DownloadString'
            - ' -command (New-Object System.Net.WebClient).DownloadFile('
            - ' -c (New-Object System.Net.WebClient).DownloadFile('
    condition: selection
falsepositives:
    - Software installers that pull packages from remote systems and execute them
level: high