Firewall Rule Update Via Netsh.EXE

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: X__Junior (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects execution of netsh with the "advfirewall" and the "set" option in order to set new values for properties of a existing rule

Known false positives

Legitimate administration activity
Software installations and removal

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	No specific technique

Telemetry coverage

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

Rule body

title: Firewall Rule Update Via Netsh.EXE
id: a70dcb37-3bee-453a-99df-d0c683151be6
status: test
description: Detects execution of netsh with the "advfirewall" and the "set" option in order to set new values for properties of a existing rule
references:
    - https://ss64.com/nt/netsh.html
author: X__Junior (Nextron Systems)
date: 2023-07-18
tags:
    - attack.defense-impairment
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\netsh.exe'
        - OriginalFileName: 'netsh.exe'
    selection_cli:
        CommandLine|contains|all:
            # Example 1: netsh advfirewall firewall set rule "group=\"Network Discovery\" " new enable=Yes"
            # Example 2: netsh advfirewall firewall set rule "group=\"File and Printer Sharing\" " new enable=Yes"
            - ' firewall '
            - ' set '
    condition: all of selection_*
falsepositives:
    - Legitimate administration activity
    - Software installations and removal
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:
        - ' firewall '
        - ' set '

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`firewall` corpus 3 (sigma 2, splunk 1) `set` corpus 4 (sigma 4)	`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"`

Firewall Rule Update Via Netsh.EXE

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`