ID | Technique | Tactic |
---|---|---|
T1021.001 | Remote Desktop Protocol | Lateral Movement |
T1021 | Remote Services | Lateral Movement |
Detection: 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.
Search
1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry WHERE (Registry.registry_path= "*\\System\\CurrentControlSet\\Services\\SharedAccess\\Parameters\\FirewallPolicy\\FirewallRules\\*" Registry.registry_value_data = "*
3|Action=Allow
4|*" Registry.registry_value_data = "*
5|Dir=In
6|*" Registry.registry_value_data = "*
7|LPort=*") BY Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid Registry.dest Registry.user
8| `drop_dm_object_name(Registry)`
9| `security_content_ctime(firstTime)`
10| `security_content_ctime(lastTime)`
11| `allow_inbound_traffic_by_firewall_rule_registry_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
Sysmon EventID 12 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
Sysmon EventID 13 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
allow_inbound_traffic_by_firewall_rule_registry_filter | search * |
allow_inbound_traffic_by_firewall_rule_registry_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Suspicious firewall allow rule modifications were detected via the registry on endpoint $dest$ by user $user$. | 25 | 50 | 50 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
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: GitHub | Version: 8