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Description

This analytic detects a potential suspicious modification of firewall rule allowing to execute specific application. This technique was identified when an adversary and red teams to bypassed firewall file execution restriction in a targetted host. Take note that this event or command can run by administrator during testing or allowing legitimate tool or application.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint- Datasource: Splunk Add-on for Sysmon
  • Last Updated: 2021-11-12
  • Author: Teoderick Contreras, Splunk
  • ID: 9a8f63a8-43ac-11ec-904c-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1562.004 Disable or Modify System Firewall Defense Evasion
T1562 Impair Defenses Defense Evasion
Kill Chain Phase
  • Reconnaissance
NIST
CIS20
CVE
1
2
3
4
5
6
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process = "*firewall*" Processes.process = "*allowedprogram*" Processes.process = "*add*" Processes.process = "*ENABLE*" by Processes.dest Processes.user Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `firewall_allowed_program_enable_filter`

Macros

The SPL above uses the following Macros:

:information_source: firewall_allowed_program_enable_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
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_id

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 Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

A network operator or systems administrator may utilize an automated or manual execution of this firewall rule that may generate false positives. Filter as needed.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
25.0 50 50 firewall allowed program commandline $process$ of $process_name$ on $dest$ by $user$

: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: 1