Allow Inbound Traffic By Firewall Rule Registry
Description
The following analytic detects suspicious modifications to firewall rule registry settings that allow inbound traffic on specific ports with a public profile. It leverages data from the Endpoint.Registry data model, focusing on registry paths and values indicative of such changes. This activity is significant as it may indicate an adversary attempting to grant remote access to a machine by modifying firewall rules. If confirmed malicious, this could enable unauthorized remote access, potentially leading to further exploitation, data exfiltration, or lateral movement within the network.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2024-05-22
- Author: Steven Dick, Teoderick Contreras, Splunk
- ID: 0a46537c-be02-11eb-92ca-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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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.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid Registry.dest Registry.user
| `drop_dm_object_name(Registry)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `allow_inbound_traffic_by_firewall_rule_registry_filter`
Macros
The SPL above uses the following Macros:
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.dest
- Registry.registry_value_name
- Registry.registry_key_name
- Registry.registry_path
- Registry.registry_value_data
- Registry.process_guid
How To Implement
To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 2.0 of the offical Sysmon TA. https://splunkbase.splunk.com/app/5709
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 $user$. |
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: 6