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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
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-07-19
  • Author: Teoderick Contreras, Splunk
  • ID: 0a46537c-be02-11eb-92ca-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1021.001 Remote Desktop Protocol Lateral Movement
T1021 Remote Services Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
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| 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 = "*
|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:

:information_source: 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 fields

List of fields required to use this analytic.

  • _time
  • Registry.registry_path
  • Registry.registry_value_name
  • Registry.registry_key_name
  • Registry.registry_value_data
  • Registry.action
  • 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

RBA

Risk Score Impact Confidence Message
25.0 50 50 Suspicious firewall allow rule modifications were detected via the registry on endpoint $dest$ by user $user$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 3