Detect Windows Allow Firewall Rule AdditionModification

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Id	056593d4-ca3b-47a7-be9d-d1d0884a1d36
Rulename	Detect Windows Allow Firewall Rule Addition/Modification
Description	This analytic rule detects any registry value creation or modification of Windows firewall registry keys to allow network traffic. This could be an indication of defense evasion by an adversary to allow network traffic to/from a compromised host.
Severity	Medium
Tactics	DefenseEvasion
Techniques	T1562
Required data connectors	CiscoSecureEndpoint CrowdStrikeFalconEndpointProtection MicrosoftThreatProtection SentinelOne TrendMicroApexOne TrendMicroApexOneAma VMwareCarbonBlack
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Malware Protection Essentials/Analytic Rules/WindowsAllowFirewallRuleAdded.yaml
Version	1.0.0
Arm template	056593d4-ca3b-47a7-be9d-d1d0884a1d36.json

KQL

// List of Windows Firewall registry keys to monitor
let firewallRegistryList = dynamic([
      'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\RestrictedServices\\Static\\System',
      'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\RestrictedServices\\Configurable\\System',
      'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Defaults\\FirewallPolicy\\FirewallRules',
      'HKEY_LOCAL_MACHINE\\SOFTWARE\\Policies\\Microsoft\\WindowsFirewall'
  ]);
_ASim_RegistryEvent
| where EventType in ('RegistryValueSet', 'RegistryKeyCreated') 
| where RegistryKey has_any (firewallRegistryList) and RegistryValueData has_all ('Action=Allow', 'Active=TRUE')
| project
    TimeGenerated,
    DvcHostname,
    ActorUsername,
    ActorUsernameType,
    ActingProcessId,
    ActingProcessName,
    ActingProcessCommandLine,
    RegistryKey,
    RegistryValue,
    RegistryValueType,
    RegistryValueData
| extend HostName = tostring(split(DvcHostname, '.')[0])
| extend DnsDomain = tostring(strcat_array(array_slice(split(DvcHostname, '.'), 1, -1), '.'))
| extend Username = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[1]), ActorUsername)
| extend NTDomain = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[0]), ActorUsername)
| extend Username = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[0]), Username)
| extend UPNSuffix = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[1]), '')
| extend RegHive = tostring(split(RegistryKey, '\\')[0]), RegKey = tostring(strcat_array(array_slice(split(RegistryKey, '\\'), 1, -1), '\\'))

YAML

description: |
    This analytic rule detects any registry value creation or modification of Windows firewall registry keys to allow network traffic. This could be an indication of defense evasion by an adversary to allow network traffic to/from a compromised host.
queryFrequency: 1h
alertDetailsOverride:
  alertDisplayNameFormat: Allow Firewall Rule {{RegistryValueData}} added at registry key {{RegKey}} on {{HostName}}
  alertDescriptionFormat: An allow Firewall Rule {{RegistryValueData}} added at registry key {{RegKey}} by {{Username}}.
query: |
  // List of Windows Firewall registry keys to monitor
  let firewallRegistryList = dynamic([
        'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\RestrictedServices\\Static\\System',
        'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\RestrictedServices\\Configurable\\System',
        'HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\SharedAccess\\Defaults\\FirewallPolicy\\FirewallRules',
        'HKEY_LOCAL_MACHINE\\SOFTWARE\\Policies\\Microsoft\\WindowsFirewall'
    ]);
  _ASim_RegistryEvent
  | where EventType in ('RegistryValueSet', 'RegistryKeyCreated') 
  | where RegistryKey has_any (firewallRegistryList) and RegistryValueData has_all ('Action=Allow', 'Active=TRUE')
  | project
      TimeGenerated,
      DvcHostname,
      ActorUsername,
      ActorUsernameType,
      ActingProcessId,
      ActingProcessName,
      ActingProcessCommandLine,
      RegistryKey,
      RegistryValue,
      RegistryValueType,
      RegistryValueData
  | extend HostName = tostring(split(DvcHostname, '.')[0])
  | extend DnsDomain = tostring(strcat_array(array_slice(split(DvcHostname, '.'), 1, -1), '.'))
  | extend Username = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[1]), ActorUsername)
  | extend NTDomain = iff(tostring(ActorUsernameType) == 'Windows', tostring(split(ActorUsername, '\\')[0]), ActorUsername)
  | extend Username = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[0]), Username)
  | extend UPNSuffix = iff(tostring(ActorUsernameType) == 'UPN', tostring(split(ActorUsername, '@')[1]), '')
  | extend RegHive = tostring(split(RegistryKey, '\\')[0]), RegKey = tostring(strcat_array(array_slice(split(RegistryKey, '\\'), 1, -1), '\\'))   
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CrowdStrikeFalconEndpointProtection
- dataTypes:
  - SecurityAlert
  connectorId: MicrosoftThreatProtection
- dataTypes:
  - SentinelOne_CL
  connectorId: SentinelOne
- dataTypes:
  - CarbonBlackEvents_CL
  connectorId: VMwareCarbonBlack
- dataTypes:
  - CiscoSecureEndpoint_CL
  connectorId: CiscoSecureEndpoint
- dataTypes:
  - TMApexOneEvent
  connectorId: TrendMicroApexOne
- dataTypes:
  - TMApexOneEvent
  connectorId: TrendMicroApexOneAma
entityMappings:
- fieldMappings:
  - columnName: HostName
    identifier: HostName
  - columnName: DnsDomain
    identifier: DnsDomain
  - columnName: NTDomain
    identifier: NTDomain
  entityType: Host
- fieldMappings:
  - columnName: Username
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  - columnName: NTDomain
    identifier: NTDomain
  entityType: Account
- fieldMappings:
  - columnName: ActingProcessId
    identifier: ProcessId
  - columnName: ActingProcessCommandLine
    identifier: CommandLine
  entityType: Process
- fieldMappings:
  - columnName: RegHive
    identifier: Hive
  - columnName: RegKey
    identifier: Key
  entityType: RegistryKey
- fieldMappings:
  - columnName: RegistryValue
    identifier: Name
  - columnName: RegistryValueData
    identifier: Value
  - columnName: RegistryValueType
    identifier: ValueType
  entityType: RegistryValue
severity: Medium
id: 056593d4-ca3b-47a7-be9d-d1d0884a1d36
relevantTechniques:
- T1562
eventGroupingSettings:
  aggregationKind: singleAlert
tactics:
- DefenseEvasion
tags:
- SchemaVersion: 0.1.2
  Schema: _ASim_RegistryEvent
queryPeriod: 1h
triggerOperator: gt
version: 1.0.0
name: Detect Windows Allow Firewall Rule Addition/Modification
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Malware Protection Essentials/Analytic Rules/WindowsAllowFirewallRuleAdded.yaml
kind: Scheduled
triggerThreshold: 0
status: Available

ARM