---
title: "Allow Inbound Traffic By Firewall Rule Registry"
excerpt: "Remote Desktop Protocol, Remote Services"
categories:
  - Endpoint
last_modified_at: 2022-01-26
toc: true
toc_label: ""
tags:
  - Remote Desktop Protocol
  - Lateral Movement
  - Remote Services
  - Lateral Movement
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  - Endpoint
---



[Try in Splunk Security Cloud](https://www.splunk.com/en_us/cyber-security.html){: .btn .btn--success}

#### Description

This analytic detects a potential suspicious modification of firewall rule registry allowing inbound traffic in specific port with public profile. This technique was identified when an adversary wants to grant remote access to a machine by allowing the traffic in a firewall rule.

- **Type**: [TTP](https://github.com/splunk/security_content/wiki/Detection-Analytic-Types)
- **Product**: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- **Datamodel**: [Endpoint](https://docs.splunk.com/Documentation/CIM/latest/User/Endpoint)
- **Last Updated**: 2022-01-26
- **Author**: Teoderick Contreras, Splunk
- **ID**: 0a46537c-be02-11eb-92ca-acde48001122


#### [ATT&CK](https://attack.mitre.org/)

| ID             | Technique        |  Tactic             |
| -------------- | ---------------- |-------------------- |
| [T1021.001](https://attack.mitre.org/techniques/T1021/001/) | Remote Desktop Protocol | Lateral Movement |

| [T1021](https://attack.mitre.org/techniques/T1021/) | Remote Services | Lateral Movement |

#### Search

```

| tstats `security_content_summariesonly` count from datamodel=Endpoint.Registry where Registry.registry_path= "*\\System\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\FirewallRules\\*" Registry.registry_value_data = "*
|Action=Allow
|*" Registry.registry_value_data = "*
|Dir=In
|*" Registry.registry_value_data = "*
|Profile=Public
|*" Registry.registry_value_data = "*
|LPort=*" by _time span=1h Registry.dest Registry.user Registry.registry_path Registry.registry_value_name Registry.process_guid Registry.registry_key_name Registry.registry_value_data 
| `drop_dm_object_name(Registry)` 
|rename process_guid as proc_guid 
|join proc_guid, _time [
| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes by _time span=1h Processes.process_id Processes.process_name Processes.process Processes.dest Processes.parent_process_name Processes.parent_process Processes.process_guid 
| `drop_dm_object_name(Processes)` 
|rename process_guid as proc_guid 
| fields _time dest user parent_process_name parent_process process_name process_path process proc_guid registry_path registry_value_name registry_value_data registry_key_name] 
| table _time dest user parent_process_name parent_process process_name process_path process proc_guid registry_path registry_value_name registry_value_data registry_key_name 
| `allow_inbound_traffic_by_firewall_rule_registry_filter`
```

#### Macros
The SPL above uses the following Macros:
* [security_content_summariesonly](https://github.com/splunk/security_content/blob/develop/macros/security_content_summariesonly.yml)

Note that `allow_inbound_traffic_by_firewall_rule_registry_filter` is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

#### Required field
* _time
* Registry.registry_path
* Registry.registry_value_name
* Registry.registry_key_name
* Registry.dest
* Registry.user


#### How To Implement
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.

#### Known False Positives
network admin may add/remove/modify public inbound firewall rule that may cause this rule to be triggered.

#### Associated Analytic story
* [Prohibited Traffic Allowed or Protocol Mismatch](/stories/prohibited_traffic_allowed_or_protocol_mismatch)


#### Kill Chain Phase
* Exploitation



#### RBA

| Risk Score  | Impact      | Confidence   | Message      |
| ----------- | ----------- |--------------|--------------|
| 3.0 | 10 | 30 | Suspicious firewall modifications were detected via the registry on endpoint $dest$ by user $user$. |


Note that risk score is calculated base on the following formula: `(Impact * Confidence)/100`



#### Reference

* [https://docs.microsoft.com/en-us/powershell/module/netsecurity/new-netfirewallrule?view=windowsserver2019-ps](https://docs.microsoft.com/en-us/powershell/module/netsecurity/new-netfirewallrule?view=windowsserver2019-ps)



#### Test Dataset
Replay any dataset to Splunk Enterprise by using our [`replay.py`](https://github.com/splunk/attack_data#using-replaypy) tool or the [UI](https://github.com/splunk/attack_data#using-ui).
Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)

* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/honeypots/casper/datasets1/windows-sysmon.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/honeypots/casper/datasets1/windows-sysmon.log)



[*source*](https://github.com/splunk/security_content/tree/develop/detections/endpoint/allow_inbound_traffic_by_firewall_rule_registry.yml) \| *version*: **2**