Firewall Rule Deleted Via Netsh.EXE

Severity: medium
Author: frack113
Source: upstream

Detects the removal of a port or application rule in the Windows Firewall configuration using netsh

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1562.004` Impair Defenses: Disable or Modify System Firewall

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\netsh.exe'
OriginalFileName: netsh.exe

Stage 2: `all of selection_cli`

CommandLine|contains: 'delete '
CommandLine|contains: firewall

Stage 3: `not 1 of filter_optional_*`

or:
CommandLine|contains: 'advfirewall firewall delete rule name="Avast Antivirus Admin Client"'
ParentImage|endswith: '\instup.exe'
CommandLine|contains: 'name=Dropbox'
ParentImage|endswith: '\Dropbox.exe'

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.

Field	Kind	Values
`CommandLine`	match	`advfirewall firewall delete rule name="Avast Antivirus Admin Client"` `delete` corpus 4 (sigma 4) `firewall` corpus 4 (sigma 4) `name=Dropbox`
`Image`	ends_with	`\netsh.exe` corpus 16 (sigma 16)
`OriginalFileName`	eq	`netsh.exe` corpus 14 (sigma 14)
`ParentImage`	ends_with	`\Dropbox.exe` corpus 2 (sigma 2) `\instup.exe`