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Detection rules › Sigma

New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet

Status
test
Severity
low
Log source
product windows, category process_creation
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects calls to the "New-NetFirewallRule" cmdlet from PowerShell in order to add a new firewall rule with an "Allow" action.

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1686.003 Disable or Modify System Firewall: Windows Host Firewall

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet
id: 51483085-0cba-46a8-837e-4416496d6971
related:
    - id: 8d31dd2e-b582-48ca-826e-dcaa2c1ca264
      type: similar
status: test
description: |
    Detects calls to the "New-NetFirewallRule" cmdlet from PowerShell in order to add a new firewall rule with an "Allow" action.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1562.004/T1562.004.md#atomic-test-24---set-a-firewall-rule-using-new-netfirewallrule
    - https://malware.news/t/the-rhysida-ransomware-activity-analysis-and-ties-to-vice-society/72170
    - https://cybersecuritynews.com/rhysida-ransomware-attacking-windows/
author: frack113
date: 2024-05-03
tags:
    - attack.defense-impairment
    - attack.t1686.003
    - detection.threat-hunting
logsource:
    category: process_creation
    product: windows
detection:
    selection_name:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
              - '\powershell_ise.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_args:
        CommandLine|contains|all:
            - 'New-NetFirewallRule '
            - ' -Action '
            - 'allow'
    condition: all of selection_*
falsepositives:
    - Administrator script
level: low

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_name

selection_name:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
          - '\powershell_ise.exe'
    - OriginalFileName:
          - 'PowerShell.EXE'
          - 'pwsh.dll'

Stage 2: selection_args

selection_args:
    CommandLine|contains|all:
        - 'New-NetFirewallRule '
        - ' -Action '
        - 'allow'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • -Action
  • New-NetFirewallRule
  • allow corpus 6 (sigma 4, splunk 2)
Imageends_with
  • \powershell.exe corpus 182 (sigma 182)
  • \powershell_ise.exe corpus 41 (sigma 41)
  • \pwsh.exe corpus 168 (sigma 168)
OriginalFileNameeq
  • PowerShell.EXE corpus 120 (sigma 84, splunk 30, elastic 6)
  • pwsh.dll corpus 112 (sigma 79, splunk 30, elastic 3)