Netsh Allow Group Policy on Microsoft Defender Firewall

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

Adversaries may modify system firewalls in order to bypass controls limiting network usage

Known false positives

Legitimate administration activity

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1686.003` Disable or Modify System Firewall: Windows Host Firewall

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Netsh Allow Group Policy on Microsoft Defender Firewall
id: 347906f3-e207-4d18-ae5b-a9403d6bcdef
status: test
description: Adversaries may modify system firewalls in order to bypass controls limiting network usage
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.004/T1562.004.md#atomic-test-3---allow-smb-and-rdp-on-microsoft-defender-firewall
    - https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/netsh-advfirewall-firewall-control-firewall-behavior
author: frack113
date: 2022-01-09
modified: 2023-02-14
tags:
    - attack.defense-impairment
    - attack.t1686.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\netsh.exe'
        - OriginalFileName: 'netsh.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'advfirewall'
            - 'firewall'
            - 'set'
            - 'rule'
            - 'group='
            - 'new'
            - 'enable=Yes'
    condition: all of selection_*
falsepositives:
    - Legitimate administration activity
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\netsh.exe'
    - OriginalFileName: 'netsh.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'advfirewall'
        - 'firewall'
        - 'set'
        - 'rule'
        - 'group='
        - 'new'
        - 'enable=Yes'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`advfirewall` corpus 7 (sigma 6, kusto 1) `enable=Yes` corpus 2 (sigma 1, splunk 1) `firewall` corpus 13 (sigma 7, splunk 6) `group=` `new` `rule` corpus 2 (sigma 2) `set` corpus 11 (sigma 10, splunk 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\netsh.exe` corpus 28 (sigma 28)	`field:"Image" kind:ends_with value:"\netsh.exe"`
`OriginalFileName`	eq	`netsh.exe` corpus 23 (sigma 14, splunk 7, elastic 2)	`field:"OriginalFileName" kind:eq value:"netsh.exe"`

Netsh Allow Group Policy on Microsoft Defender Firewall

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`